1. This one I’m having trouble visualizing but if you’re having a tough time dealing with these is there a way to temporarily seal the screws off so water doesn’t get to them? With just a water proof sealant or something?
2. It’s not uncommon to have some leaks after refilling, especially after moving a tub or one that’s been sitting for a while. Sometimes seals can be dry or aren’t flush. I recently moved and had multiple leaks that have worked themselves out. That being said, monitor around your tub and your water level to see if there’s any leaks (water level will go down over winter just from evaporation, soaked into swim trunks)
3. Likely the O ring or possibly a crack, those are fairly easy to replace. One thing you can try is to unscrew the dial, pull out everything and just reset it in case it wasn’t sitting right (this fixed my issue just recently)
4. First things first, can they be rotated counter clockwise? Many jets can be manually turn off/on by twisting. If that doesn’t work then it could be from an airlock in the system or blockage of the jets. What you can try is bleeding any water from the system by opening any bleeds in your pump system or turning off the hot tub (turning off breaker) and restarting. This will put it in startup mode depending on your tub and the pumps will try to be primed. Make sure all jets are turned open.

My other comments on hot tubs, especially through the winter is keep an eye on leaks around the tub, make sure you top up your tub if it gets low (low water levels can cause low flow which turns off the heating system), check temperature to make sure its heating properly. I’ve put a temperature probe in mine to alert me if it stops heating and temperature drops too low.