In all honesty you don't need to keep temps up very long. If it were me I'd do a Herms system. I thought about doing a RIMS for a long time. But the simplicity of a HERMS made me change my mind. It works great. Although I don't really use it as much as I initially thought. I get full conversion after 20 min, so It's really there just to bring up temp while recirc before boil. (saves propane
) I just used my old 25' copper immersion chiller and some compression fittings (soon to be brazed in place) then attached my QD's and works flawless. It's more of a cool project than a necessity. 2 tier for batch sparges. Not sure why people want to fly sparge these days? I get 85% efficiency from my batch with recirc.
As far as the pump all you really need is a valve on the outlet of the pump to adjust flow. Drain valves on your keggles. Then just normal fittings (QD's)on everything else. you'll just move the hoses unless you hard tube the thing. Then that is a nightmare of valves and what not. But really cool when done. Good Luck
Since you are a plumber and have experience with soldering though I'd definitely suggest soldering/brazing your fittings on those keggles. Sorry for the plug, but I just did this and it is amazing! I hated weldless!