What the ele teaches you: to read the forums before picking your profession
I still recommend necros first for those that don't want to frontline (Ritualists too). Necros have barbs and minions very early on.
Mesmers are more elite skill reliant (AP sin spam, Clumsiness/Ineptitude spam, Keystone, FD, PI, etc) and reactive stuff (Empathy, Backfire) isn't all that impressive in normal mode. See http://www.gwpvx.com/Special:PrefixIndex/Build:Me/
Playing monk is a lost cause with the 7 hero update. Mo/W and dump points in tactics for shield to PvP with. It works especially well if you UA (Unyielding Aura) or Healing Burst since you can easily do
* 12+1+1 DF, 8+1 heal, 8+1 prot, 7 tac for UA bar with gift + dismiss
* 12+1+1 Heal, 9+1 DF, 6+1 prot, 7 tac (or 6 tac and 7+1 prot) with Healing Burst
...if you find a 5/13 shield like I did you can play around with the attributes more or just deal with 0 tac (you still get 8 armor).UA (Unyielding Aura) is hands down the best bar for reliable party heals outside of Avatar of Dwayna at the moment. With Divine Healing and Heaven's Delight on 12 recharge you have 6 recharge between the two of them and possibly 3 if your equipment's halves skill recharge kicks in.Chapter
As far as which chapter to start I still think Nightfall is the most polished experience in terms of explaining things. Factions is a day or two rush to 20 if you play it quick. Prophecies takes about two weeks of casual play just to reach 20 whereas you can get to 20 in a week in Nightfall without a sweat. Nightfall also gives you a minor vigor rune among other things.
The thing about Prophecies is the last attribute point quests are at the endgame which I do not like at all. Having to beat 85% of the game to get to Southern Shiverpeaks the normal way is going to be tiring for most people. Not to mention some people forgo the attribute points because they don't know about the quest in Crystal Desert either, meaning they are permanently handicapped. Prophecies does a lot of hand-holding as far as missions but not with respect to attribute point quests.
I made a guide starting in NF a while ago that might need updating: http://wiki.guildwars.com/wiki/User:...beginner_guide
Positioning
Frontline: Dervish, Assassin, Warrior
Midline: Mesmer, Necro, Ritualist, Paragon, Ranger
Backline: Monk, Ritualist w/ restoration magic
Playing front/mid/backline is different. However, heros don't play frontline well so you get used to them mingling.
Playing professions
Playing a profession is a lot different than having one as a hero. Hero AI is limited, so mesmer bars need to be simplified and you can't run bars on them which require paying attention to skill descriptions (energy intense bars like Assassin's Promise). You can get away with Mo/W on a hero only if you put 5 energy stuff with >4 recharge on their bars. If you put 1 recharge Healing Whisper then they will spam it and you need to dump points in inspiration magic for energy management like Power drain and Leech signet.