I find it's the pre/post-season parts that tend to take me the longest time. All that scouting to arrange, all the hopeful youngsters on trial to sort through...fun times!
Yep, all beta saves will carry over to the full game (I just won the FA Trophy with Gateshead, wouldn't want to lose that), think of it as the full release but with a few occasional (but quickly fixed) bugs.
Good luck finishing a career in FM, I've been playing them since Championship Manager 3...