Most of this has already been stated in this thread, but as a fellow new-guy, I'll give you my take as well.
As for size of humidor, this is personal preference. I guess it really comes down to how often you honestly believe you'll smoke. For me, I got a small 25 count desktop humidor. I keep about 8-10 smokes in there at any given time. I really do not understand these guys that stock pile 400 cigars in their house. But you must take into account the expansion factor, anyone that's bought a humidor says to say the same things as anyone that's bought an aquarium ("i started small, and kept buying bigger and bigger, and would have saved a bunch if i just went big at the start"). But again, gage it to how often you're really going to smoke. If you smoke 1 a week, do you really think you need to store 150 of them? Let the shop worry about that.
Aging is another thing that everyone will give you a different answer on. If it's coming from a shop with a walk in humidor, I'll buy it the day I smoke it. If it's coming mail order or something, the common theme on the boards seems to be to stick it in the humidor for 10-14 days to let it get its humidity set to your levels. Again, until you're really into things and know what you're doing, you probably won't be aging the proper sticks in the proper way anyways, so why bother with the space and expense? You'll figure it out in time.
Whoever said to find a shop and talk to the owner, I think is on the money. I'm lucky enough to have a grocery store near me with a walk in humidor and a few knowledgeable people behind the counter. Head in, tell them what you like/don't like, experiences you've had, and they'll steer you in the right direction. And if they don't, at least you can blame someone other than yourself
In the army, we have a saying about "eyes and ears open, mouth shut" - that's what I do on the forum. If I have a pressing question, I use the knowledge that's here, otherwise, you'll learn a ton just by stopping in every day or two and seeing what other people's experiences are and have been, and learning from their successes and failures.
Welcome to the club!