1. If u are using only morghs than begin your own troop tree from swadian/vaegir/etc recruits
for example:
swadian recruit upgrades to swadian militia/custom unit 2
vaegir recruit upgrades to vaegir militia/custom unit 2
You hire recruits from other kingdoms in your villages and upgrade them into your custom troops. But i
highly reccomend to use module system and make all correctly. There is guide about hiring custom troops in own kingdom.
2. OSP is very easy to employ. write "load_mod_resouce = "osp name here" " in your module.ini and add item with help of morghs (copy item and then change meshes, flags, etc). Or you can easily add items with help of MS.
One thing you should know. MS is not a Python. It has it's own language and it is not very hard to learn. Only compiler is real python.
Hope my answers were enougth for u