Looking forward to see what you have in mind, thank you and good luck.
Never been an issue in total war games even though its perfectly doable
I know say they are working on it but tbf they have said that for over a year.
You dont "need" them but you can use the item files I linked if you dont want the game to be unbalanced when it comes to armor that is not set up for the most recent RBM armor values. For example a visored full helm has 150 armor with RBM while it only has 50 armor and all mods such as veagir armory is balanced for vanilla not RBM
You can use the items files from here to make vaegir (and vlandian armory) compatible with RBM
Very true I also play exclusively with RBM and its clear that the biggest crux of that mod is how much heavy armor troops will outperform light armored, rendering them almost useless in comparision. I suspect this problem is one of the reasons why TW hasent done anything about the armors in Bannlord so far, because it would mean they have to implement some kind of stamina system.
Always depends on gear, In custom battle all units are tier 3. So genrally bow at tier 3 vs armor of tier 3 bows will not do too much damage( they will stil shread tier 2/1 though) however tier 5/6 bow or crossbow are able to kill tier 5/6 armored infantry well in my campaign games
The battles arent that much longer but they are better paced imo. In the beginning when both lines meet the initial fighting time is longer untill one side gets the upper hand(kill more men) which is when it comes down to the last standing (heavy armored) "veterens" with better morale, which will either get overwhelmed or manage to kill opposing side if they are of bad enough quailty/too hurt and flee/get cut down. But as a rough estimate I would say that battles are normally 30%-50% longer depending on how many armored troops are on each side and terrain. I am also using the AI module of the mod so that might have an influence beacuse the ai might be more prone to fallback or reposition after initial skirmishing compared to vanilla, cant say for sure.