Hey Sean, thanks for your question. No worries about being a newbie.
1) You already have a theme! Since close up is your expertise, you should have no trouble picking effects either. Why do you ask us if what you have said is true? I apologise if this sounds blunt - and it isn't intended to come across as harsh - but the point is that you have all the tools you need. You don't need to go out and learn stuff just for this. You should have the material already - work with what you have, because trying to cram something for a show is rarely a good idea, and also because we can give you suggestions but you may as well pick effects out of a hat and they'd be just as good, since we don't know you, and finally because it's probably better to not accept a show if you don't have an idea about what you want to do.
So that's some more or less practical advice - the gist of it, stay with what you know, and what you like.
But there's something more important here I think we need to address. It will explain my answer above in more detail. There's a hidden assumption in your question, which is not a good one to make. You've asked, "What effects do you think would look good close up?" The hidden assumption here is that effects are inherently interesting, and that the power of magic is in the effect. This is mostly incorrect. There are effects that are inherently stronger than others. But the strongest effect can be made weak, and a weaker effect made strong. How? By the performer. This is important to recognise because we must always be aware of the fact that it is the performer, and not the magic, which is interesting.
This is why I advise you to stick with what you know - because it is more 'your' material than anything I or anyone else could ever suggest to you. It would definitely help to know more about you - but over an internet forum, we really can't come close to knowing you like this. It is not the effect, but the performer, around which the success or failure of a performance is based. It is not an effect which is strong, but the performer that makes it so. Connect with your audience, show some personality, and create entertainment - entertainment does not lie within a deck of cards, or some half dollars, or a length of rope.
2) Ok, let's take this as an example of a running theme. Visual illusions. How would we create a performance around this theme (incidentally, see? You have a theme, you can create ideas for themes!)? Well, I would approach it a different way. I don't think the way to go is to purely go for visual effects. The reason why is that we are talking about two different definitions of visual. When you talk about visual illusions, one thinks of blurring the line between reality and, well, whatever you want that "other" world to be. You're talking about a perceptual shift - something like what you would see in Donnie Darko or Shutter Island. That's your thematic idea from what you've said. But, visual effects are merely ones that involve strong images and visuals. Visual here describes not perception of the world around us, but rather, more solid images, a series of visual moments. Simply put, visual effects don't necessarily result in visual illusions.
Something that comes to mind for example when I think about visual illusions, are effects to do with dreams. Why are dreams illogical? What about people's dreams? Can you perhaps predict a dream someone had? Or perhaps you can reenact in some way a dream that you ask them to construct. Alternatively, I think of effects where a spectator is asked to look at something - but sees something different to what is actually there. What can you do along these lines?
I think you would agree, for example, that whilst Daniel Madison's effect Crunk (sold here as a 1-on-1) is a visual effect, it has absolutely nothing to do with visual illusion. The same is true for many visual effects. A visual illusion in fact pertains to the plot. A visual effect pertains to the construction of the effect. Therefore, they are two unrelated things.
3) There are no strict ones, except perhaps, "Connect with your audience". I mean that in all seriousness.
Most prefer an opening magic effect to be short, to the point, and a demonstration of what you can achieve. Most also prefer to use their strongest effect as their closer. This will be a stock answer you may receive.
I do not think it surprising by this stage to say that I'm not sure that's the right way to approach it, although this advice may, generally, be correct.
As I mentioned before - the effect is secondary to the performer. The way I proceed when putting together a routine around a theme is this. I look at the theme. I consider what I want to do with the theme - how do I want it to begin, to progress, and to end. What do I want to say about the theme, and how is it personified in my performance?
Then, I consider my effects. When I have a theme, as you do, I consider effects not so much in terms of magic, or time, but rather, in terms of what they do. For example, I may want my first effect to introduce the theme, as well as myself - who I am and what I do. This is often done best when done succinctly - so again, it may well be true that a quick effect is best - but firstly, this is not always the case, and secondly, I think it's better to think of it in the way I mention above - in terms of the theme, and the role of the trick. I may then want my second effect to develop on this basic theme, and explore some aspects of it. I may later want to significantly change the mood of the piece. I may want to demonstrate a specific point. I will choose my effects so that they change the pace, or the mood, or the direction of my performance. It is, of course, only a given that I begin with a pool of strong effects. Therefore, I do not consider the "strength" of effects, this is a given; rather, again, I consider the role of the effects.
Taking, for example, the closer - this is the very last thing they will see of you, and your routine based around this theme! This is the very last image they will have of you and your magic. My goal in this case is very often to close on a very specific feeling, to extend the theme with the effect, and to leave on a unique, emotional and memorable note. Sometimes, it may be on the note of astonishment, sometimes on the nature of impossibility, and sometimes, on the feeling of achievement and empowerment - it simply depends on what I am performing, and how I am performing it. The first two are two different versions of the same trick, suited to two different themes. The second is an entirely different trick as well as presentation.
Most importantly, as I mentioned at the start - stay connected. Whilst performing for a friend today, he pulled out his phone and showed me a photo he took of the climax of my closer - an Out of this World routine - that I performed for him a year ago. He also mentioned to me that his best friend, another friend of mine who was present that evening, had been relaying stories about the effect to a girl he currently has a crush on - and who, incidentally, refuses to believe that it is possible. Said friend, having seen the effect performed twice, insisted that it was indeed impossible, but that it happened anyway. Suffice to say, it made me very happy indeed.
This is not the effect of the trick - this is the effect of a connection.
When people remember magic tricks, they remember an image, which will become the basis of their memory and their emotion. From this image, they will derive a meaning, which gives magic purpose. These images are, invariable, images that SPEAK TO US. When people tell other people about magic tricks, they want to convey how they felt - NOT what they saw. This is only possible when magic connects.