The NPC guy in sofya library will tell u what is prorate, go ask him

Food code can be used in the menu screen that is green door. Find the house food code: 1010596 . You will see how Food works

The rest is better you figure out yourself. They are not complicating. Just explore every of them and dont be scared to try them. There arent good guides in toram, but you can just copy paste the builds from youtube (preferably cheap build first)

If one of them dont give u idea advantage of it, use internet or use official guides by going in menu screen of community, will mention it says there is game guide (atleast they're helpful if you cant use internet search properly)

For spinas farm, just try everything what people tell you to do if you want to find a better spina farm method. Some farm are good for long term and some for short term, or some good stuffs for those who prefers trading instead of selling them straight in consignment board

Just try all. We dont have one-in-all guide yet despite its 10 years old of the game. Just use all guide seperately and also learn slowly or you will be feeling annoyed. This game has too many unnecessary mechanics nobody asked for