Hello!
You're right, the boutique and its items are almost completely absent (I said almost, because you can pretty much get 40 specks of light when you hit 65, but that's rather insignificant). Also rarely, such as during the Allods anniversary event, they hand out items like Iridescent Jar which allows you to create more reincarnations. But nothing game changing.
You also can't buy mount food, they're not needed. Mounts here don't level up, you don't need to feed them - they're at their peak right as you get it.
Caster Healer is more of a DPS class, it's very powerful - especially with the new reincarnation skill of Pridens. I'm not an expert on their builds, I guess you should check out the Archetypes/Healer sections - there has just been a PMB event, which should mean plenty of builds.
As for the question about which classes are good for support, that's a pretty complex one, depending on how do you define support. Every class has certain skills, rubies, utilities and buffs that the party can benefit from.
On the League side currently there're two major guilds.
Avarice which is an international guild and Anka (sorry if I misspelled, still working on memorizing the name) which is a Turkish guild - I believe.
I'm not sure if Anka has a site yet, but here's a link for Avarice:
link