Q: Are there restrictions as to what mods can be put on an item based on the type of item(i.e , armor, shield, jewlery, etc)
A: Yes. Whatever properties an item can normally have as random loot is what it can have imbued.
Exceptions:
You can imbue runic only properties such as velocity and balanced on bows and crossbows. It was easier to handle imbuing with bows and crossbows to do that, plus it felt more consistent.
Looks like kits will only be good for making base items to imbue or items to unravel.