- Do you extreme hard pan left and right on the overheads and/or toms?
I use Boz Digital Labs Pan Knob for panning rather than the one built into your DAW. This features a crossover to keep frequencies below the cutoff centered and only pans the frequencies above it. It's cheap and absolutely worth it. Such a better solution for most things. With that plugin in mind; Overheads are almost hard panned left and right unless I'm going for a very old school thing, in which case I'll narrow them up. Toms should be placed in the stereo image such that the close mics and the toms position in the overheads is coincident. The exception to this is if I need extra width on tom-heavy parts or rolls across the kit I might pan them slightly wider than their placement in the overheads. It's rare though. Things sound tighter when you use the overheads' image to place the toms in the stereo field.
Keep in mind that the overhead mic'ing technique will play a huge part in this. A coincident pair can be hard panned and still sound narrow. A spaced pair can be hard panned and you might end up with phase issues or a weird "hole" in the center feeling. These days I'm almost always using a modified Recorderman setup in my studio which can get nice and wide, but not overly so. Worry more about getting the snare top the same distance from both overhead capsules as that's something that often gets left out and then people wonder why their backbeat doesn't sound punchy.
- Do you pan drums from the drummers perspective or the audience?
Totally personal preference. I'm an engineer and a drummer, so I prefer them panned from the drummer's perspective. Pick which one you like best and go with it. If anyone outside the band questions your panning direction just tell them the drummer is left-handed
Another consideration is the arrangement. If the song sits on the hi-hats more than the ride, you might intentionally pan the drums to put the hats on the side of the mix that has the least going on so you can better utilize the space.
- Do you add reverb to the snare or keep it dry?
I'll commonly have an aux send on the snare top that goes to the same plate reverb that I'm sending the lead vocal to. Both snares and vocals absolutely LOVE plate reverb. A little goes a long way, so be judicious and use a smart phone or laptop speakers to check the reverb level on a test mix. High fidelity mains have a way of burying reverb in all the other lush frequencies, but a smart phone or laptop will reveal them in a very painful way. Get it to be just audible on a smart phone speaker and it's probably just right for most applications. If you're doing an 80s thing you can get away with a lot more snare reverb since it's part of the decade's style. Early to mid 90s thing? Lots of reverb on all the drums in a sort of garage rock kind of way was a very popular technique. Early 00s thing? Lots of bone dry drum recordings around that time. It all depends on what you're going for.
- Do you mic both the top and bottom side of your snare? bottom mic phase reversed
I almost always mic the bottom snare mic and I almost always mute it in the mix. I learned from Simon Phillips that bottom mics on snares typically sound bad. As a bonus, using just one mic per source will reduce potential phase incoherency issues. Since I've gone to mixing with just the top head I've found that my mixes have greatly improved. If you do use a bottom mic you can try flipping phase, but a phase alignment plugin like Auto Align from Soundradix can be a big help.
- Do you gate any/all drums or record/mix them wide open?
Depends. Are you going for a Ringo thing or a Vinnie Paul thing? For most productions I tend to do some gating of the kick, snare and toms, but generally speaking a little bleed is fine. You might get a little excess top end on the attack of the drums but I've never found it to be a deal breaker.
- Do you pre or post process drums with compressors? I have hardware and plugins
I don't, but if you know what you're doing AND you know what's going to work for the arrangement, it can be a fine approach. I'd rather just use good mics that are well positioned, send them to high quality preamps and converters, and then go from there.