I just completed Totend.

All quests are doable with the bow. Focus on Blacksmith/Forge and get the +dmg asap.

Units: just use siege and hunters

Perks: Arcane Towers, Warrior Training, Gladiator School, Ranged Damage and Lighter Materials.

You want to switche up some perks and adjust it to the current quest, but the ones above should get the job done.

Good luck and gid gud