When you book a fast pass, if you stay onsite, can you do it 60 days out plus 10 (length of stay) like for dining (180 plus 10) or do you have to do them one day at a time as they come available?
It's 60 days plus the length of your stay. So if you go for two weeks it's actually 60 + 14..the number of days that you can make FPs for is limited to the number of days you have valid entry for (unlimited for an AP, 7 days doe a 7 day pass, etc)
According to bullet point #2 under Booking Windows and Scheduling in mesaboy's FP+ thread, you can book for the entire length of your stay up to 14 days: