As far as recommended eq settings for recording bluegrass, you just kind of have to do a lot of critical listening and learn to identify things you like, then figure out how to get them into your own tracks.
One thing that someone told me that really helped was to record with the headphones turned as low as possible. The tendency when they're turned up loud is to play more softly, and if you're playing softly, you are not pulling all the tone out that your instrument has on tap. And try lots of mics. My own philosophy is "less is more." Less eq, less reverb, less compression means more natural sound. If you are not getting good sounds down, all the equalization in the world wont help.
That said, I'll share a couple things that work for **my picking style** on **my instruments** playing **my songs** (your mileage may vary...) :
On guitar (my best Martin is rosewood and has scalloped braces), i roll off gently everything below about 200hz and boost a little around 12k right before rolling off everything higher.
On mandolin (I build mandolins... right now my main instrument is Englemann spruce and maple) I do nothing but cut off everything about 10 or 12k depending on the mic and room.
On banjo - the two banjo players I work with, one plays a Gibson Mastertone and the other a very nice Deering. They come properly eq'd from the factory.
Finally, acoustic bass - it depends a whole bunch on the bass. I like to really boost the lows around 50 hz, slightly boosting (2-4db) everything up to around 2k, then leave it flat from 5k on up. From there, I'll tweak a little.
Sorry for being so long-winded. I hope this helps you find your sound.