Should there be other possible character appearances beside the normal character skins? For example one could turn into a ghoul after completing some kind of special quest or become a mutant after takin a dose of FEV.

For example: Player "Evilbadman" wants to become a ghoul, either because he wants to do some more roleplay or maybe because he just thinks its cool to walk around with a three in his head. Now that he became a ghould he notice, that he can't run anymore and has just half of the maximum Hit Points a normal player has. But his Perception and Small Gun skill is very good now and also his Radiation Resistance.

The reason why people should change their skin or even choose it from beginning isn't the topic now but what about this in general? Would you like to see such a variety of skins within the game and if so, should the skin also affect players skills and perks?

Personally I would love it if we were able to play as Ghouls in a game like this, heck not even for a statistical advantage.
Too many games these days go for the Gritty super buff meat head Orc, or female characters get curvier or so hot that it'd make Barbie jealous (but I won't complain about that) but without the occasional thing thats ugly as sin to compare it to its not as sharp.
And for them RPing bunch out there it'd give them a leg to stand on in such a game how ever it evolves.

Yes! to many types of character possibilities. The great thing about an MMO is it CAN change over time. If no one wants to play a certain class/ race well then thats fine. but at least give the player the option. MMO's... MMO's never change...

I'd prefer an all human world, (possibly with the exception that people can turn into super mutants and ghouls, at considerable risk and effort).

It would be fun if there only where humans first, but you would be able to have the choice to change later on - Like a lvl 20(depending on lvlsystem, a lvl20 character in fallout is pretty high) character quest where you will be dipped, BUT there is a chance that you will die... permanently AND you will have a major risk of loosing almost all your intelligence (int is set to 1) but your strength will be boosted. But there will be the very small chance of actually preserving your intelligence, but that should be like 0.001% or something >,<

I personally think it would be cool to be able to change. For example:

You can do a certain quest that turns into a ghoul at a certain level. Ghouls have less hp, are slower, and have some "rep" loss and/or gain, but have better small guns skill, better perception, better crafting? and radiation heals them(allowing them into a new city or reigon maybe?)

Same with super mutants. Lose almost all intel/perception/medicine/science. Get really high strength/endurance/big guns/explosives and again rep gain/losses.

Ability to join factions could be similar. Some factions offer different items but make some cities hostile.