I do about 5-10 a day myself. For #1, ask someone you know, if anyone, who is a contractor or in construction to give you general numbers. I asked my cousin who has been in construction to give me general figures for rehab costs for cabinets, floors, roofs, etc. And a lot of this is online.
For #3, focus on a city/area and you will get to know the neighborhood. I focused on one city to understand the rent prices, general home prices, and other key factors. Now, I've moved onto another city, and another. Once you practice in the same area, you'll start to know rental rates, what houses typically go for, and other details. For example, in the area that I look at, most houses are older, have 3 Bed/1 Bath, but there is room for another full bath and probably a half, and I know how much adding a bath would cost, and then other things that I would typically do in the house.
So, the key is to practice and it just sinks in after X-amount of analyzing deals. Good luck!