How should i EQ distorted guitars parts?
Don't - as much as chess was saying not to fiddle with the microphone, I think his point in saying to change the settings on your guitar and amp were referring to the fact that it sounds a LOT better when you adjust your setup to suit the recording, verses thinking that the amp sounds good in the room, so it
better sound good on tape, and if it doesn't, start using additive and destructive processing on the final track.
usually when i record guitar it will sound really muddy in the low end and i have to find what frequency it is and take a few dB off.
If it is really so muddy that turning down the bass on the amp + maybe changing your guitar settings + moving the mic around doesn't help, looks like you'll have to keep performing that EQ alteration. Nothing to be done about it. The overall theme here is "Don't EQ when you can fix the source, and if the source sucks enough that it can't be fixed, THEN go ahead and start making changes post-recording".
if i've got two guitar tracks each one panned hard(well, 70 percent) left and right how should i eq it so that the two guitars aren't fighting against each other?
Do i cut some frequences in one guitar and boost them on the other?
Have you actually done this or are you just asking for the sake of asking?
I'd say worry about getting a single, mono recording sounding good before you go trying to "beef things up" by double-tracking what apparently sounds like shit.
Unfortunately, shit times 2 does not equal amazing guitar, it equals even more shit (by a factor of about 2

)
The other point here is that, while moving a mic around on an amp will of course change the tone of the recording, you are making the assumption that it is
everything. It is not - the fight here seemed to get out of hand from the get-go, so no one could step back and realize that the sound you are trying to fix is a combination of things - mic placement, and the sound of the rig.
Like I said, if you can't get a decent mono recording with one mic, there's something wrong with the setup. If you don't think your guitar and amp are to blame (most people don't), then try a different mic. Try a different dynamic, or throw a condenser on there.
As for the placement of those mics, the only place I've found that gets an even tone is pointed at the cone, about halfway between the dustcap and the edge of the speaker. Slide in one direction or the other to get a bassier, or thinner tone, respectively. Chess's point (and I am making major assumptions here), is that when you move that mic one inch in one or the other direction, you don't wind up with a monumental change in tone. Its there, but there isn't going to be that one magical place that sounds 100x better than everywhere else on the amp.
Don't bother putting three mics on the damn thing, as you will probably wind up introducing phase issues to the problem (mics at different distances from the amp, even on the same side, can end up cancelling out certain frequencies, and then it gets reaaal confusing). For now, try one mic, try moving it around until it is as close as you think you can get to the tone you hear near the amp. Then, start fiddling with your guitar and amp settings.