I can't offer a lot of advice because I haven't played a cleric-type build in a while. I can understand your concern, as wanting STR, INT and SPD will tax your attribute resources heavily and you'll probably want to depend on gear for a lot of those bonuses. In particular you'll want Movement if your intent is to move around the battlefield.
I'm also uncertain what you see as the role of this character in combat. Other than healing, what else are you doing? Are you going to be a major damage dealer?
Can Lone Wolf really be used with the 4-player mod? Even if that works, it seems kinda cheaty, because if 4-players still works, you're getting all the benefits with none of the drawbacks.
Escapist is not a great Talent, most of the time you can just move away and flee combat normally.
Getting +2 Hydro at character creation seems like an odd choice. Are you sure there are no other abilities you really want to take? I'm not sure what benefit you'll be getting out of taking 2 levels in Hydro immediately. It can't be for the second healing spell, which you can't even use until level 7.
Some skills which might be good to help with your tanking:
Water of Life (Hydro 1) - +3 CON for 3 turns.
Become Air (Aero 2) - +50% Physical resist for 3 turns.
Elemental Absorption (Witch 2) - +50% Elemental Resist for 3 turns.
