VEVOR Oxygen Non-Barrier PEX Tubing 300 Ft White 3/4 Inch PEX Pipe Radiant Heat Floor EVOH Pex-B Heat Durable Plumbing Flexible for Residential Commercial Heating Plumbing

Yes, This should work well for your supply line from the well pump to your house.

Yes it definitely will. Be sure to protect the pipe with a sleeve or insulation when it's buried.

I would say that you would need more volume than just a three-quarter pipe

It should be fine to use it outdoors, but will need insulated if used during winter.

I use mine outdoors. I’m planning on burying it.

I've had mine buried outdoors for 3 years now. Works fine. I don't know about being exposed to sun light though.