More Expensive Furniture and increased Salaries

I'm sorry to say that your furniture goal is basically impossible due to the amount of work involved....unless you learn how to batch process it. The normal way to do it is to create an Override file for a single object and make it more expensive on the Studio page, then in the Warehouse delete everything but the Object Definition for each swatch so you don't override anything else. Even if you skipped deleting the other files because you don't intend to release it or use other object overrides, it still requires a lot of manual labor and time. So if you want to make it go quicker, you need to extract all the Object Definitions with Game File Cruiser then make either a program or script that can read the files, maybe check for the tags so fridges are more expensive than counters, etc., and adjust the price for you. Since you don't know anything about programming, that's probably the place to start. You might get away with learning Python to do it since it's pretty easy compared to most other languages, but I don't know how you'd make it read Sims 4 files for that task. Most creators use...I think C#? to make their S4 modding programs. If you choose Python, download PyCharm as it also comes with a beginner plugin that could help.

If you're still interested in the career salary changes, you should learn to mod through Scarlet's tutorials (starting on page 2): simsvip.com/category/the-sims-4/how-to-create-a-mod/page/2/

C# isn't needed for modding, Python is for scripts, but C# seems to be what most people use to make programs for Sims 4, at least as far as I can tell (I know very little about how program making works). Good luck! If you do succeed I highly recommend releasing it as I'm sure a lot of other people would like it too. Oh, and try checking S4pe, which is open source and you should be able to use the related files to read objects. That way you don't have to figure that part out and can focus on simply making the program.