Ive been taking my son, 7, up there since he was 3 and he always has a great time. You can park for the practices across the street at the Skydome. If you get there about 30 mins before the Friday practice you'll have a change at getting some autographs, as well as after the practice. Some guys will sign a good 30-45 mins after. For the Saturday autograph session, it all depends on whose signatures you want to get. Basically they have tables set up with a seat for each player and you stand in line for whoever you want to get. If you want to get say Fitz or Dockett count on getting there at least an hour early. In the past my son has gone for quantity, so we havnt stood in the Fitz,Warner, Boldin, etc lines. This year he wants to go early and get Fitz. Plenty of seating at the practices, if you have camp chairs or a blanket they help but are not a nessecity. The have some games set up for the kids that are free, and also sell concessions.
As for where to stay, the town is full of hotels. Im pretty cheap so we usually get something in the $60-$70 range, there are a lot of no frills places, that are clean and basic and not bad for a night or two. I usually just go on hotels.com and read reviews. The Woodlands Raddison is probably the nicest hotel up there or the Drury, i've stayed at the Woodlands but not the Drury, they are probably $150+. Lots of good places to eat, we usually end up at Peter Piper one night, not that its good but the boy likes it. If you have any other questions or want to know about a particular hotel or restaurant let me know.