You can definitely schedule back-to-back sessions. There's always plenty of time to get where you want between sessions.
Last year's Scripting session was full. I don't think they refused anybody, but I saw a lot of people standing in the back. You should register for your sessions as that would theoretically be the way to attend a session that cannot fit everybody in the room, but I have no knowledge as if it is strictly enforced or not. I've been able to get in every session I planned to attend last year. NI scans your badge at the entrance of most sessions, but that has probably more to do with making sure you've paid the conference fees or for marketing/statistics, than keeping you out of the room.
I had a hard time waking up last year, so I could not get a seat for the first keynote! Get up early if you're not a VIP.
As for sessions recommendations, I agree completely with Daklu's list.
I would also add John Lokanis' "Practical Applications of Web Services in LabVIEW " presentation on Wednesday afternoon.