Just a note on HA AI - forum member Caba'drin has written a lot of good pseudo-AI tweaks, one of which is a skirmish mode which causes units to avoid melee at all costs. It's not perfect, but it's a marked improvement on Native Warband's hurrdurr charge headlong into a pile of huscarls HA tactics. There's also a script for smarter lance and polearm usage, which was another huge annoyance for me personally.
Basically, while you can't really delve into the hardcoded AI stuff, the newest module system does offer a lot of options for tweaking surface-level bot behavior.
Also, I'm very excited to see NE moving to Warband. It was my favorite mod for 1.011, and I'm sure it'll be a hit in WB as well. Cheers, modders. You guys are awesome.