1. Search HomeDepot for "PEX tubing". (or Google)

2. You don't have to bury the line, but I assumed it might be running across lawn, and that you'd prefer not to leave it exposed.

3. The circulator could NOT perform the initial lift. Once the lines were FILLED, it could handle the circulation. But if an air lock occurred, you'd have to replicate the startup. To lift 40', you need 25 psi. That's a design problem what would require special consideration. Many AG pumps won't reliably generate 25 psi.

4. Could solar contractors do it? No, not as a rule. Or, yes, but only with a massively oversized and inefficient pump. I probably shouldn't have mentioned it -- I know how to do it, because (a) I was a plumber, (b) I've done controls and energy management work, (c) I have a good practical knowledge of circulatory hydraulics, (d) I have a degree in engineering management (abt 3/4 of a full engineering degree) and remember a fair bit of it. That's an uncommon combination.

'Techy' DIY types, who are willing to do a LOT of leg work, and are able to do the trial-and-error could succeed. But finding a contractor to do it? Not really.

But, you could ask. There ARE some very sharp pool guys out there; they are just the exception, rather than the rule. But you might be lucky, and find one.

Sorry for the problem.