You do not need a charter or to go to a special area, though you can create a guild by speaking to a Guild Registrar in a city.
You will need to have 1 silver in order to create a guild. Then all you need to do is open the Guild window (G by default), choose a name (31 character limit) and guild tag (an abbreviation that will show up next to your character name, up to 4 characters), and that's it.
Note that guild members don't even have to have be on the same Home World (server) as you, though you do need to be on the same Home World if you wish to play World vs. World together.
The default maximize size for a guild is 50 members. In order to increase this size, you will need to speak to a Guild Registrar. The following table from the official wiki lists the costs and upgrades as follows:
Tier Membership Cap Cost
1 50 1 Silver
2 100 1 Silver
3 200 10 Silver
4 300 1 Gold
5 400 1 Gold
6 500 2 Gold
Preface
I've not played TERA, so I can't do a comparison. I've also only played BWE1 of GW2 recently and I tried Guardian and Elementalist.
Aim and Dodge
Guild Wars 2 has been specifically designed with active combat in mind. As such you must keep moving at all times when in combat, either by circling your enemy, backing up, or using Endurance to dodge.
If you stand toe-to-toe with enemies you'll get put down quickly.
If you can circle enemies and stay mobile it's possible to put down +3's without even taking a hit! I played a Guardian in the BWE1 and using a Scepter & Shield combo it was possible to take on large groups without taking much damage just by making sure to run around lots.
The main thing to remember is the 5 D's of Guild Wars 2, dodge, duck, dip, dive and dodge! Just remember that your Endurance is limited and you'll only be able to dodge about 3 times in a row before it'll run out. I would strongly suggest strafing around enemies, even in melee and only using dodge to avoid large attacks.
As the developers have said, the combat is designed to be very active and you'll need to watch your enemies animations to spot when attacks are coming in order to evade them. The best example is Ettins using their big smash attack, where the animation starts with a gathering flash around them before they launch the attack. It's visual cues like this which are your keys to using dodge effectively. Check out the Ranger's Serpent Strike skill video.
Also be sure to understand the ground markers. White are positive effects and will usually grant a boon (positive buffs) to you. Red markers are enemy AoE markers and will usually damage you of give you conditions (negative debuff), so you will need to run out of these areas or use dodge to roll out of them.
Targeting and Hitting
As for aiming, your attacks are always targeted at your currently selected target. So as long as you have an active target you will not need to target your attacks. There are a few types of attacks which do need targeting, usually Targeted AoE attacks. When these skills are activated they will change your cursor into an image of the area, which will allow you to place the skills effect. Do be aware that there is a fast-cast option in the game options which will activate these skills at your current cursor position, thus avoiding the need to hit the skill and then place the effect. These types of skills also apply to walls, which in some cases are automatic, like the Guardian's Line of Warding and some are placed like the Elementalist's Flamewall.
Do be aware that if you do not have a selected target you will still be able to activate skills and they can damage enemies but you'll struggle to deal proper damage and in most cases will die. This happened to me a few times in the BWE1.
Ranged and Melee
This is a hotly contented issue and spawned a huge thread on the forums. Mainly as most people felt that Ranged was far more useful than Melee in the BWE1. The developers agreed with this and said that the dynamics of ranged vs melee will be tweaked as the game progresses.
The function of the two modes of damage dealing are the same. They both have a range, which you can see by looking at the skill bar, if the number is white, you can use the skill, and if it's red you are out of range.
There are a few points to note with some things such as scepters shoot a projectile which tracks the ground, thus you are unable to fire it up or down. Rangers have a huge range and pretty much everyone just stuck with Long Bow in BWE1. I ended up using Scepter on my beta Guardian simply because it was easier than using a melee weapon. I tried Greatsword, Mace, Hammer and Sword, but none of these were as easy. Don't get me wrong, they were all effective, but you'll take more hits from melee enemies as you can strafe/kite them around.
Thanks
If you read all this and got here, reward yourself with a brew and a bikkit.
Best Answer
As already mentioned, combos are a powerful incentive if correctly used - for example, you can keep up 25 might stacks on the entire group with a minimal amount of players blasting through a fire field. This is like having an extra set of power/malice gear.
Reward-wise, more players means more kills without a decrease in experience or rewards. It's probably more than just a linear progression, since you won't waste time dodging (not to mention you'll never die again).
Also, hearts are completed much faster. To give an example, one of the hearts in Caledon Forest allows you to progress by killing undead. Those undead are spawned by pulling their hands - which are instanced. A solo player can pull a hand, kill the spawn, then move on to the next hand (2 progression points, one for the hand and one for the kill). A party of three can each pull the same hand (instanced), then aoe on the three spawns - not only will they kill faster, each of them will get double progression (1 point for the pull, 1*3 for the kills). While the solo player will have to stay around for a while, the group will pull the 4-5 hands in the area around them and be done with the quest.