1) We have an actual thread dedicated to sharing horrible DF-stories: http://forum.square-enix.com/ffxiv/t...ry.-Let-s-vent. No need to create a seperate thread each time you run into idiots in a dungeon

2) No, obviously not all tanks in this game are jerks.

3) Jerkish behaviour is not exclusive to tanks either - you can meet impatient DPS and healers (who might pull for you) just as likely.

4) Personally, I'd still bring a tank and a DPS for each run, to ensure fast and smooth clears. At least thats what I'm doing - I tank, my boyfriend comes as DPS that way I can set a fast pace and he ensures that stuff actually dies quick enough to keep said pace.

5) As I sort of mentioned earlier: This still wont prevent you from running into jerks or outright bad people from time to time. Nothing you can really do to avoid that, beside only going into dungeons as full group. So my advice here is: Just move on. You'll meet those people on occassion, if its really getting out of hand: Report. If they're hindering your run or getting really abusive: Kick them.
But dont waste a second thought on them. If you need to vent - I linked a thread dedicated to that. But getting a thicker skin, shrugging things like that off and just enjoying your game is the best thing you can do.
At least in my experience stuff like this happens rarely enough. Dont let it get to you - theres no way to avoid jerks, they're not linked to a specific role after all. (I'd only recommend to bring a tank so you have the most "control" over the run and can ensure that stuff gets pulled fast - nothing enrages me as much as a tank taking a minute to pull stuff, but the only thing you ensure by queuing up as tank - or healer or DPS for that matter - is that this role is filled by a competent person. You can still end up with a jerkish dragoon or whitemage, even if you queue as tank)

6) Proper communication can go a long way aswell - informing your party about your lag-issues as soon as they appear. They might believe you or not, but seriously... "I've known her for 3 years!" sounds like a boyfriend making a shallow excuse for his girlfriend rather than she telling the party herself "Sorry, got a lag-spike here!"
Again, might be "personal preference", but I would disregard a bf defending his gf much, much faster than she informing the party herself about a technical issue she got right now. It speaks way more to her own competence if she just says that instead of you telling the party how long you've known her.

Bottomline: Jerks will be jerks; jerks can fill any role and you'll avoid them by avoiding randoms; we have a thread to vent if you need to.