Tail lift shouldn't be a problem with newer Rics, as far as I've read here. I have a 2011 4003 and the tail isn't lifting. I'm using Ric factory roundwounds on it.
There is a small gap between the end of the tail and the body, which I believe is normal, as the body is not a perfectly flat surface, or so it's been said here.
If you really want to do something about it you can drill two new holes in the back corners and screw it down. Some people do that, but if I were you I would wait and see if you have a problem, first. Most of us don't.
As for flats, can't help you there. I'm a rounds-only guy. Somebody, maybe it was Ric5, once said that putting flats on a Geddy Jazz Bass is like putting snow tires on a Corvette. I feel the same way about my Ric, but if I were playing Beatles covers I would reconsider my opinion.
Thanks!
I was really just worried about the tail because I've heard a few people complaining that they get tail lift on newer Ricks within 3-5 months. If it happens I'll just take it to the local guitar tech.
I didn't like the Rickenbacker strings that were on it when I tested it. I've been using flats for almost the entire time I've played bass. I might check out some Rounds, but I heard you have to be careful with higher tension strings (I'll try to find some low-tension ones)