I agree with backgrounds. Keep it similar and the same throughout for consistancy. As for picture backgrounds, sometimes you can get away with it as long as you make it a watermark.
Titles (excluding the opening slide) in my opinion should be on the slide before anything else i.e. it's there when you change the slide so that not only you, but thoses you are presenting to, know what you're going to talk about before you do. Also, it will keep you right too.
Re: animation of text. It too should be kept consistant throughout. As for the animation of pictures, I would recommend that it appears via dissolve or something along those lines. Try to avoid the fly in ones. And sometimes sounds go great with images as well (if it will allow it)
Really I guess it's whatever going to suit the topic that you choose, but I gladly help you if I can
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