RDM/THF probably wouldn't work in exp. parties, probably if you farm for items treasure hunter would be good.

RDM also don't melee in exp. parties. Early on you see a lot of them do that because they have the same mentality as you; I want a balance of melee and magic. But the truth is their melee really falls short through most of the game. They are mainly used to cast Refresh, enfeeble / debuff spells, help healing and help magic bursting off skill chains.

I know there's the whole argument that "I can be whatever combination I want" but the truth is the community doesn't really allow you to, so you won't get anywhere in the game.

By the way, don't take stats into concideration when choosing a race and job.

Edit: You change your job and subjob from nomad moogles and the moogle in your Mog House (or rented one in other cities). You can switch between the first 6 jobs, but you have to do quests to unlock the advanced jobs after level 30.

And you do a quest at level 18 that most parties will help you with, to be able to get a subjob.

Also, just out of curiosity, what advance job are you thinking of taking up? ^^