Re-plumbing pump questions

I just bought my home and I am having problems getting enough suction to vacuum my in ground 25000 gal pool. There is an air leak on the suction side and a water leak on pressure side of pump. I am going to replace the plumbing from the inlet pipe from ground to the filter. My question is what type of supplies to use.

Which type of PVC? Schedule 40?

Special type of PVC cement?

What type of sealant to use on threaded connections? Teflon tape or?

Also the pipe from pump to filter seems to have extra turns that are not needed. I would post a picture but i don't see that option. It goes up from pump, turns to right, up, right, down, and right into filter tank. Would it not be better to just go up from pump and turn right into the filter tank?

Thanks in advance for reading.