1)
For armors, you basically have to choose between "dodge" and "tank".
- If you often get hit, P-modded red is probably the greateast usual suit you'll get. (The ideal is AOP, or Powered-red, +P if possible)
- If you manage to get hit rarely, you can afford to use weaker suits. I stopped using tactical armors, but usually play with green (both have give a good movespeed, a the cost of a dubious protection).
Your best suit when playing that way is a phaseshift (with AOP, of course :))
Overall, I wouldn't advise to B-mod an armor, since it costs movespeed. Unless you want to make it nanofiber, but IMO, they are worthless without an added P (so I'd forget it for MAD)
Don't underestimate the movespeed. There's a reason why I prefer green over blue or red : it makes a huge difference !
I often switch to red around hell, since revenants (and mancubi) can be deadly, but by that time, I usually have A-modded tac boots, and A modded armor.
And yep, outside of AO100+, I always go for Tac boots (+A : I don't mod assemblies without WK2 usually).
2)
Not much advices to give here, but you might consider playing masterless. As you noticed, masteries can be quite... constraining.
About MAD, I think I'd pick BER, but I guess anything is OK.
For MSS, I'd say WK (since gun really suck, and some improvements really help), then, anything.
3)
SOB is crap for melee
(and BFGs :o))SOB can be paired with SOG, but I doubt it's really worth it if you go pistols only. If you also use shotguns or rapid fire, it can be worth it... but then, I'm not sure you should pick SOG :)
SOB is of course very efficient with rapid fire, since it's what it has been designed for. Just skip the 5th level to avoid getting knockback.
SOB is quite good with shotguns, but I'm not sure it's necessary with a MAD build, which already gives an insane dmg output.
I consider SOB is "the best skill". Well, this is quite subjective, of course, but it looks like the most efficient to play damageless, which is more or less what most angels challenges is about, so I ended-up picking it on every run.
Here is a sample of SOB effect on shotguns :
I always play with shotguns, and now try to get Hell's arena pwnage medal with each of my N! runs. Since I suck, I use INT2+SOB1, but I often fail at knocking some monster back, and get hit or have to run because of my crappy damages.- This doesn't happen when I play HA with SOB2, since failing to knockback is really rare, and would "never" happen with SOB3.
- Without SOB, I just have too much difficulties to knock-back even a simple demon. I often get hit, and can't abuse of cornershooting, which makes the game harder and more complicated (like... needing to think and have good placements instead of just mindlessly alternating phases pressing "f f r" (kill) and ", 5" (stand still waiting for xp to come))
Its worth noting that a P roughly equals two levels of SOB for a shotgun, but I still love that early SOB2 or 3, since you get it WAY before the P mods, and it stacks anyway (try an elephant gun, or a P3 regular shotty, and you'll understand how fun it can be :)
Overall, about shotguns :
- I personally stick with regular shotty all game long, but the best is the tactical one, which is more versatile. I just hate having to pump (and have crappy damages) until it's fully modded.
- Assault is the theorical best, of course, but you'll often find it too late, and it kinda needs the P to balance that missing dice anyway, so Tac is great enough.
- Super shotty and Jackhammer are in separate leagues. Both too rare to be reliable, but they give great damages (I don't really use either of them anymore, but this is another story :p)
- Plasma is... well, good for gibbing the mortuary (and maybe for the reloading-bug-abuse), but crap elsewhere, since it ruins your covers, and eats way too much plasma.