So...got the helm of Serenity and now am wandering around a bit. I found Bela and the Peak and accepted Bela's mission. This is after accepting the T'rang mission. Is it too soon to have come here? Does taking up Bela's mission put me in dutch? Or is it alright to explore this area knowing I won't be able to make endgame now anyway?

Not sure quite how far you are, but unless you have the 3 artifacts, you won't be able to complete the peak anyway, even if you're able to pick the 8 cylinder gate locks up there and live through fighting the hordes behind the gates. Shouldn't hurt to look around as far as you can though. Save first.. ;)

It won't hurt any other quest endeavor taking Bela's quest, and it's necessary to complete it anyway, unless you prefer blowing Dominus to smithereens later.. :D

Elara