DIY fret levelling?

How hard is it to get it right with no experience? And what tools do I need?

I just bought a lightly used Stratocaster player. I can't seem to get a decent string action without fret buzz around the 12th fret, even after adjusting the truss rod. I suspect the problem is a few high frets around fret 15.

Also the fret ends needs filing, but I guess thats an easier job?