How long is the Game and how much can I do? 

FernoFX

Level 3 Affinity (maybe will be raised in future?)

Hubert

Gregor

Orderic

Hanth

Valdo

Giant Loyd

Ghart

19 Undies to Collect

Next update in December (Maybe more Characters Affinity added? Story continues)

My guess on who gets next Affinity updates (these have three unlocked affinity squares when talking with them)

Horace (Wizard)

Beton (Soldier)

Tristan and Hector (The Twins that guard the Gate)

or maybe some totally new characters?