Hello J1285!

Welcome to the forum!
Q1: They didn't find mortars and/ or had no ammo for it and/or had no opportunity to use 'em.
Q2: DeadPixel nails it.

Questions in general: Try to keep them in the discussion-section of the forum - 'cause of Spoiler-alter and stuff ... Also the place there is a lot more lively ... ^^

All the best!
Liam