How badly will it mess up my site if I've been uploading via FP but need to do one FTP so a friend can look at my code and see what's messed up? According to my ISP, it'll fry my site, but I find that hard to believe... won't I just have to reinstall FP extensions when I want to upload again?

On the same note, if FTP is successful, should I just continue to do it that way?

Thanks in advance!