so does doing quest/missions help to level up your avatar. also, how do people get titles? is at level 60 when people get titles?

your level is the same as the one of your most powerfull pet, pets that were bough higher level then your actual level dosn't apply here.

Pets earn some amount of xp when in mission so yes, it theory, you can level up your personal level from it if one of your mission pets earn enough to go past level 55.

titles are not tied to level at all, they are special reward for accomplishing special actions during events, some of the titles sutch as 'sea shell collector' are now retired due to the activity not being avaalable anymore and some are linked to scrolls you can use to add said title to your title list.