Low oil pressure

Long story short, I would not do most of that. If you are putting a higher volume oil pump, that may not be a good idea. You only need more volume of oil flowing through the engine when you are increasing the horsepower and need the additional protection. This alone will probably be okay but if you do this then you definitely don't want to add thicker oil or any other thickening additives. Basically you want the oil to flow easily through the engine and doing this will possibly create to high of oil pressure and then you are going to have different issues.

If you already bought the pump then just replace the pump if that is the only issue with all the new gaskets. I would not replace the bearings just because you are there or the oil sensor if there is no issue with the current one. You can replace the pick up tube if you want to but normally you just have to clean off the screen unless there is a large amount of debris that went through it.

Basically my mind set would be to only fix what is broken at this point. Otherwise, there would be no ending. I would not worry about trying to predict what may happen and repair it now while you have the pan off. These types of repairs are not maintenance items which means you should only replace them when there is an issue.

Hopefully this answers your questions. I know it may not be what you want to hear but I would recommend against anything other then what is needed.

In theory it will not but if it were me, I would get the OEM or equivalent pump on this older vehicle. The main reason is, you put more pressure to the bearings and seals and you may start having leaks that you can't resolve. In other words, it is just opening the door to potential issues when you don't have too.