sites moding & siege weapons

[Pocus]

I wonder if it is planned to mod the sites, modifying gem incomes and recrutable units. With that in mind, it would allows the addition of new units on maps without having to change themes. Any nation (on a scripted map) would then be able to get the new units if they possess the modded sites. For example an Ulm empire could start with a master smith site, which allows the construction of catapults (fire boulders, and is worth 50 units in siege, I prefer that to the Ulm engineer).

Along this trend, I'm thrilled to mod new units with 0 strat move : catapults, ballistae. These would be only buildable in national castles, and would help you tremendously in case of sieges.

3 related questions :

I have not seen a tag in the new units proposed (Hoburgs) which allow you to give a sound to the unit though. Or perhaps the unit attack comes with attached sound?

does a hard limit exists to the number of units a nation possesses?

when we mod a theme, can we just alterate slightly an existing one, or should we redefine all the parameters of the race?