Returning to the game after a long dry period, few questions

I havent played this game in ~3-4 years. I recently got a good deal on Prophecies/ Faction/ Nightfall, logged in for some pvp in RA, and realized this game has changed a ton.. I don't think I lasted more then 20 seconds in any round. So, I'm taking a step back, going through Nightfalls PvE, and trying to learn the ropes all over again. Heres the questions:

1.) Are any classes at all 'in demand' for Pve groups? When I played it seemed like every group was looking for a monk, and Mesmers had a rough time finding a spot. I'm only asking because I'm older now, have a job n stuff, and its hard to find time to play - would rather not spend that time LFG.

2.) I remember spending a lot of time trying to cap obscure skills from enemies. Does this still happen alot? What is the quickest way to get a good variety of skills? (assuming I'm playing nightfall).

3.) If I make a character in Nightfall, can I go back and play through prophecies or factions with the same character?

Thanks all!

1)It is pretty much the same,monks are still wanted as ussual and mesmers are disliked because most people dont know how to use them and/or what they can be good at.

2)Yes it still happens and is still the same way,Nightfall is good for capping elites since most maps are packed with a bunch of bosses.When you get to the Sunspear Sanctuary for example, from there there will be about 5/6 maps you can exit tooall with about 6 to 12 bosses.If your a dervish for example those areas alone give you all the Form elites and a few extras.

3)Yes you can go to the other campaigns and go play there, there are a few quests you will not be able to do and in Phropecies you will not be able to play pre-searing but your not missing anything major.In Phropecies you will be brught to lion's arch which is about 1/4 into the game so you will have to backtrack thru the campaign if you want to do all the missions and get all the outpost and towns.In factions you will be brought to Kaineng City which is still pretty early in the game,there is only about 4 missions to do there and a couple of extra towns to get there before your caught up.

In Normal Mode, there's only one character class really, which is the Atleasthesnotahenchie class. If someone's looking for a group, they'll take pretty much anyone who wants to join.

Since it seems you're starting in Nightfall I would go ahead and just finish off that campaign before starting towards Proph. and Factions. Not only will you gain valuable heros that you can use when you hop campaigns but also a reasonable sum of loot/cash/gold from just going straight through a campaign.

I would also suggest making a visit to PvX Wiki, although most of the builds there will be cross-campaign it should still give you a decent idea of how the builds have progressed since you last played.

Creating a pool of skills is easier; there are hero skill trainers and skill tomes that help a lot (cheap/fast).

Monks are always popular. There are other specialized builds that are in demand, but that's usually later on in the game.
The good news is that you can get Heroes in Nightfall and a good team of you + 3 heroes + 4 Henchmen is all you need. No need to LFG unless you want to, and you can play any class that suits your fancy.
http://guildwars.wikia.com/wiki/Hero

You are probably thinking of "elite" skills, which need to be captured from bosses. Regular skills can be gotten from Skill Trainers and Hero Skill Trainers as you go along.

Yes. Once you get to Consulate Docks you can get small quests to take you to Prophecies or Factions. (Plus pick up a few more Heroes - Olias (necro) and Zenmai (assassin) and M.O.X at some point.)

1) Monks are still in demand for pve groups, and mesmers still have it rough. Like someone previously said though, many people will take anyone, as you are better than a hench. There are pve-skills now, which make any player desirable over hench, if someone is looking to get a group. Also, work on your heroes, they are a great addition that wasn't around 3-4 years ago.

2) Elite skills are not so out of the way, as they were back in the Prophecies days. Nightfall and Factions are much easier to skill cap. There are still some good elites to get from Proph, but nowadays you can use elite tomes. Just ask if you have questions about the tomes...

3) Yes you can, and you will probably want to, once the Title Bug bites you.