Best file format workflow for Final Cut Pro 7 on Maveriks
Likely your issues were stemming from trying to edit with H264 files.  This is something that FCP hates!  Convert all your h264 footage to ProRes before you start editing (using Compressor, MPEG Streamclip, or the awesome Magic Bullet Grinder) and then edit with the ProRes files.  Output your final 'Master File' as ProRes and then use Compressor to encode that file to various formats for delivery.