Post processing rythm guitars

HP/LP and usually a small narrow cut around 3.5k, something about my cab I guess. HP/LP is all you should really need. In general, the less processing your tracks need the better your mix is gonna be... The ultimate goal should be to get everything sounding so perfect in tracking that all you do in the mix is set levels and pan, but of course that's a bit unrealistic. Still, that's the goal you should have in mind when tracking. NEVER track something INTENDING on processing it later, post processing should be a last resort.
 
All depends really.
Sometimes I get away with zero post processing apart from LP/HP filter on guitar amp sims, other times I need post EQ and slight compression.
With post processing, it can be anything really, from small cuts/boosts, to more major cuts and boosts, depending on what the mix needs and what amp sim I'm using.
Typically for POD Farm, that seems to require very minimal post processing because there is so much tweakability in there with the 4 band semi-parametric EQ anyway.
I might make small cuts at around 1.2KHz, 2.5KHz and maybe around 3KHz.
Another recent thing I did, with 8505 (which as we know isn't that tweakable) I ended up boosting some stuff up to 7dB to get what I was looking for. Boosts around the lower mids, 4KHz (for brightness) and 7Khz (for air).

As for HP/LP filtering, typically I'll set the HP to 100Hz most of the time, but for LP I might use anything between 10KHz to 12.5KHz, depending on the application
 
If Jeff were here, he would say "your high pass frequency depends greatly on the fundamental of the lowest string of your guitar." You should try that before you knock out all the lows.

Guitars and players make phenomenal differences. A great player will make your life quite easy.

I only HP/LP. Work on the tone at the source.
 
Better the player the less post processing is needed. Hp/lp, gentle eq and comp sometimes to tame wild notes. Saturation to taste. Sometimes the tiniest amount of verb as well.