Class, pets and mounts

You can't capture mounts, you can BUY mounts for any class.
Cleric skills are kind of expensive (if you want to concentrate on both attack and support skills). Supporting your squad mates takes lots of mana so you might have to waste a lot of time on harvesting herbs or spend money to buy potions. I do not recommend it for first time players. Veno is the easiest class to play due to their pets (pet tanks - Veno attacks, they use almost no potions), and the skills are relatively cheap, except for some high lvl ones. Veno can get several useful support skills too, they can give spark to squad mates, bramble the tank so he reflects damage, use amplify damage and ironwood scarab on bosses so they take more damage. And of course, pulling bosses with your pet. (: If you manage to get a Hercules pet, you can even tank most bosses (optional, but recommended for higher lvls).

Heck, do both classes. That's what I do. Plus I have a psychic too. :-D

My veno often makes the money and gets the gear, and then I pass it down to my cleric, whom I keep around 10 levels below the veno (gear gets updated every 10 levels), which then gets passed on to my psychic, who's around 10 levels below the cleric. An Account Stash Stone makes this much easier, since it allows you to pass items between characters on the same server and account at the banker, but it's $15, so make sure you're going to stick with both classes before you spend any money on it.