Completed in 35 months

Well, for a beginner, you're incredibly persistent and patient! :) My personal record is 29 months on the "Jedi story" map (but it's not easy to complete quickly). A normal time for a typical XL-sized map with a dungeon is up to 12 months; after that, playing becomes too tedious. So, you should start with simpler maps.
I also had an overflow of money once. However, I reloaded the save before this incident and changed the resources (in this situation, you can also recruit troops in all cities, even if they are not needed); after that, the overflow did not occur. And yes: the overflow occurs after 2 billion gold, so it is a very rare phenomenon.
Regarding assembled artifacts: have you definitely freed up all the slots they occupy? Some sets cannot be worn together. If you can't figure it out, post screenshots, and we'll take a look.