1) Since there is currently no cap or diminishing returns on Resilience, generally there's no set value. Most folks on my realm look at 2k as the absolute minimum for playing in anything rated, and 3k+ is generally accepted as "a good start." So, I'd call this personal preference. Generally you stack as much of it as you can, along with your primary stat.
I believe there is a possibility that DR will be added to Resilience in 4.1, which would change this answer.
2) Players definitely spec differently for different kinds of fights, and gear may follow suit. Arenas allow you to spec knowing what your teammates will bring to the match, allowing you to take talents that complement them. Battlegrounds are more chaotic, requiring more independence and balance. World PvP is even more chaotic than BGs, though I don't think you'd spec that differently for them. (Would love to hear some wPvP experts chime in on this.) There are also enchants and devices that have tremendous utility in regular Battlegrounds and World PvP which don't work in either Arenas or Rated Battlegrounds, or perhaps will work in Rated BGs but not Arenas.
I believe you need separate evaluations for Arena and BGs/World PvP, at a minimum.
3) You need to take into account several factors with stat weighting. I'm going to talk about Warlocks, specifically, since they're my main class.
- Spell Penetration is a must to overcome resistances in Arena, and useful in BGs. Casters should stack to 195/6 to overcome most resistance auras/buffs. The tricky part is Mages - they have Mage Armor, which gets them to 240, which I don't see a lot of people stacking to overcome. Stacking your gear to overcome a single classes' defense doesn't make a lot of sense, as that extra 44 points will usually come at a high itemization cost.
- You covered Hit to 4%, though extra Hit wasn't always wasted - it used to be useful against Rogue's CoS, though that's a buggy spell and I don't know if that is still the case.
- My itemization of Hit (to cap) > Spell Pen (to 195) > Intellect = Resilience > Haste >>> Crit = Mastery is based off of the PvE analysis of the secondary stats for Affliction, but that doesn't make it optimal for all Warlock specs. Crit has burst value, something that will be hard to model, but is totally viable in PvP. If you get a lucky string of crits in PvE, it will be averaged out over the course of a 5-8 minute long boss fight. If you get a string of lucky crits in PvP, you can take out an opposing healer, put incredible pressure on a DPS... Crit is an itemization that should be given some thought. You may want to see if specific classes should have "Crit Build" options.
4) Every character in PvP should have an escape trinket ability, period. If they're not human, they should have the 2-minute PvP trinket. Even an older 2-minute trinket (with lower Resilience) is better than none at all.
Not every spec is going to be able to make good use of on-demand trinkets, though they're generally better so you can burst your damage. DoT classes can use both fairly well, since spellpower is dynamically calculated, so a proc effect is still very good (and can sometimes be even better over long fights.)
Keep in mind the shared CDs of PvP trinkets, as well. Two Battlemaster trinkets will share the same CD, so their effect is reduced. Oddly, some of the proc trinkets share an ICD (Bloodthirsty Insignia of Dominance), too, so you may want to encourage people to have two different trinkets.
The last point is that... well... there are some very, very good PvE trinkets out there. I've considered getting the Darkmoon Card: Volcano for myself, as it's so very good. I don't know how to handle this one effectively - when is it better to step away from the PvP vendor and get a great PvE trinket? That's a tough call to make.
5) Not once they've discovered Resilience, they don't.
6) Absolutely for Arenas, Yes for Rated Battlegrounds, Probably Yes for unrated BGs and World PvP. 195 is the usual target.
7) Pity Arena Junkies redesigned their site a few weeks back, or I would point you there. The most common Affliction specs I've seen are 31/7/3 for Arenas and 32/7/2 or 34/7/0 for BGs. I'll have to look into Destro to see what's up, mine is 2/3/36 but I haven't been playing it.