It's nigh on impossible to answer your questions as everyone has a unique Mac setup. As well as hardware and OS, performance depends on:
There really are so many variables. The only good piece of advice anyone can give you is to play around with your settings and see what suits your game style. But, to answer your individual questions:
Display on full screen or windowed ( I do not have windowed full screen mode on my laptop I don’t know why and it should have have all 3 display modes)
- whichever providers the best overall, smooth, lag free performance for you
Which resolution should I set it as if I should play with full or windowed?
- the one that looks the best but doesn't impact performance
Why I don’t have other option than default for Refresh Rate?
- because it just isn't there. I don't think I've ever seen another option on any of my Macs over the last 6/7 years
Should I turn on Vertical Sync or uncheck it?
- on to reduce tearing
Which Graphic Quality is best for this type of Mac? Ultra, High, Medium, Low or Custom but which custom quality?
- whichever one provides the best, lag free gaming experience. The graphics chip is very low spec.
Should I turn on Uncompressed Sim Textures, Post Processing Effects and Laptop Mode or turn them off?
- depends how you want your game to look. If turning them on reduces performance, turn them off
What affects the game clock/time to not sync properly with and without mods also and how do I fix this
- look in the bug forum https://answers.ea.com/t5/Bug-Reports/bd-p/The-Sims-4-Bugs
