So, I built something and moved in the Oldie but I realized I haven't put in the bin to save for anytime. So, I moved them to the family bin and then saved the house because I heard saving it while the sims are there can corrupt the game. However, I then panicked because I realized if I were to save it after a family lived there would it also corrupt, I looked into post about avoiding corruption and it says that it can corrupt if I don't erase the off world loiters, not sure what that is. I then looked into a discussion that says it won't corrupt the game, which confused me. I only recently moved in the Oldies, but I'm not sure if there's anything to corrupt it, if so, how do I fix it?

Clean it out of sim references then package.
https://modthesims.info/showthread.php?t=609188 Two methods, manual or more automatic.

Is this used for personal use (not sharing this) lots too?

Essential for sharing, but very handy for personal use - it keeps your game clean.
The Lot Compressor is very easy to use anyway - and if you had it, you could have cleaned that lot in seconds before putting it into the bin.