1) I'm a bit confused about omf and mxf files. what's the difference? i recently installed mc 2.8 and now all the new files are mxf, the old ones are omf, should i convert the old ones in mxf or leave them like they are, I also noticed that in media tool I can only see mxf files. is there a way to see both?

2) second question: is there a way to set my timeline to a certain bpm to edit a music video and have some kind of grid on the timeline that shows where all the beats are?

thanks

 1)  Don't worry about it. You can mix and match OMF and MXF on the same timeline without any problems. I've been doing it for 4 years without any issues. MXF is the new file format that super cedes OMF due to the requirements of HD, XDCAM, P2, tapeless file exchange and the like. But from now on, create all your media in MXF, including audio. The system limits maximum files in the MXF numerical folders to 5,000 files automatically, creating new numerical folders as needed. Avid can manage multiple smaller media databases much better than it can with one gigantic one. This translates into better system performance and response time.

2) The closest thing to what you desire is to activate the audio waveforms in the timeline and use those to find your BPMs.

If you ever used to export omf sequences with embedded media you will have to trasncode it all upon export or use AAF sequences instead.