azraelck
Angel of Cookies!
Dragonmarks are feats you can take on new characters after you run a character through a certain Marketplace quest, yes. You have to take them either when you get a new feat (which you should get another one at level 6) or have the feat swapped out.
Fred the Mindflayer can swap feats out for you, but it costs a good bit. More useful later to dump feats that you take at low levels to make surviving to the high levels easier, but otherwise have limited value.
Quite frankly, they're useless save for the Halfling one. The Halfling Mark of Healing gives you CLW, CSW, and Heal for free, and for anyone who has a spare three feats can help out quite a bit. The others are situational at best, and generally a waste of scarce feat slots.
But as a Fighter you get more feats than anyone else, so you could spare the slots, if you truly want to.
Fred the Mindflayer can swap feats out for you, but it costs a good bit. More useful later to dump feats that you take at low levels to make surviving to the high levels easier, but otherwise have limited value.
Quite frankly, they're useless save for the Halfling one. The Halfling Mark of Healing gives you CLW, CSW, and Heal for free, and for anyone who has a spare three feats can help out quite a bit. The others are situational at best, and generally a waste of scarce feat slots.
But as a Fighter you get more feats than anyone else, so you could spare the slots, if you truly want to.