Are there a very long line that old man take a long wait? I have bad legs and knees..

Depends on the rides. The common rides have short lines. The rollercoasters are popular with lines past an hour for many. Fast pass will get you on most rides in 1/4 of time

I would suggest the fast passes the lines can get to 30-45 min on the weekdays without it. We didnt wait in line for more than 5-10 min if that. I couldn't imagine the weekends

If you get there early then no