I need some help installing a new water softener, RO system and acid neutralizer. I'll post pics as the process is completed and hopefully this thread can serve as a nice guide for the future. I have all the main equipment now and need to move on to the main plumbing part. I'll have to come back around for the programing help at the end but first I need everything hooked up. For Ph I have a Fleck 5600 with 1 cuft. I have the WS1 at 32k with SST-60 resin for the softener. A PuroTech RO system and an inline sand seperator. The RO system also has a pump if I need to install it. This is a small ranch house with one bathroom and a simple shower with a regular shower head. There is only two of us living here. I have 3/4 copper coming in and want to use CPVC and PEX as much as possible. I'm a DIYer but have no plumbing experience. The water comes in at one side of the house from the city and drain goes out to a septic system at the opposite side of the house. Also on the drain side of the house is a tankless hot water heater. The kitchen sink is on the main supply side of the house and the bathroom is on the septic side of the house. (60 to 70 feet apart) I'll post the main questions I have to start below and I'll provide the details need as they come up.

My understanding is that the sediment filter is installed first in line, then the neutralizer and then the softener. Is that correct?

I have to run the drain line about 70 feet to the septic drain. I've read that 3/4 PVC is the smart choice. Is that correct? Can the neutralizer and the water softener share the same 3/4 inch PVC drain? Also, how much should this drain line slope?

Should the RO system be fed softened water?

What size plumping pipes should I buy? Everything branches off a main copper pipe that is 3/4 inches now. I don't want the hose bibs softened so I'm even thinking of adding in manifolds if they make sense.

Which is a better choice CPVC vs PEX after the main copper to connect to the water filters?

I'm thinking shark bite fittings for copper to whatever but whats a good PEX connection system? I've read up on it and have a hydronic heating system thats using a crimp system that seems ok but has had some leaking problems. I didn't install that system by the way.

What information can I provide to help out here? Thanks!