Just wanted to write a few mechanics I saw that aren't really explained ingame, and the team I used. Might help someone out.
Using food in bulk for EXP gives bonus exp at certain brackets- there might be more but the ones I noticed were at 3k,5k,10k,20k,30k. The 30k also gives +1 potential.
The potential is a percent boost to stats. +5 is 5%, can go over 100.
Searching all villages reveals a castle with a guest unit, they don't get scenes and the only way to up their potential is with food. Notable ones are from your starting country (best sword unit), Asai-Asakura (gun unit before Nobunaga), Ashikaga (tank unit before postgame, only 1 hp though). Don't think any others are really worth the effort, aside from completion.
Best units IMO are Kaihime from hojo, typeless lance makes for a great tank. Yoshimoto from Imagawa is the best archer, Nobunaga from Oda is the best gunner (other options are available, but only much later), and either Tanukihime from Tokugawa (better stats but higher deploy cost, can only summon 3 at a time from full bar) or Motonari from Mori (a much later territory) for magic AoE. Bombs can probably work too, but I never used them. Best are probably Suzukori from Iga, or Oichi from Asai-Asakura.