Veganaise is a great mayo substitute, it's really hard to tell the difference, at least for me.
Soy cheeses are a toughy. Like PinkMafia said, it's all pretty much trial by error. I've tried some that I absolutely hate, and have had some that I like okay. I haven't found one that I absolutely love. I've been vegan for 2 and a half years and have learned not to miss cheese.
I always use EnerG egg replacer. It works really great for baking or anytime you would ordinarily use an egg as a binder. It also lasts a long time.
One random but HUGE suggestion for vegan soy yogurt is anything by Whole Soy Company. Their soy yogurt tastes better than ANY OTHER soy yogurt I've ever tried, and it's so close to real yogurt that my dad couldn't even tell the difference (which says a lot! lol).
Most grocery stores have started to carry organic or locally baked breads. I've found that they are usually vegan, and are made w/out preservatives and random animal ingredients. When I'm at school, I live off of these breads, but when I'm home I make my own bread in a bread machine. If you end up liking veganism (I hope you do!!) I'd definitely recommend investing in a bread machine to make your own cruelty free breads, and you can also make really yummy homemade pizza dough!
**While on the topic of pizza, lol... here's a really tasty recipe for tomato sauce!
-roughly chop a few roma tomatoes and saute with a good coating of EVOO, basal, oregano, salt and pepper until the tomatoes are all mushy, bubbly and delicious. great on pizza, pasta, bruschetta, etc.
Good luck with your 30 day trial run and hopefully you like it enough to maintain it!