A valve on the inbound side is a bad idea - you risk running the pump unprimed. One on the outbound side is all you need.
For connections, I tried one of these for the connection into the whirlpool, but I had to drill them out (there was a cross bar inside) so the hops wouldn't clog.
These work well, but are overpriced and the o-rings are easy to lose. I'm sure McMaster has an equivalent - but I didn't do the search.
Atomic Dog Brewery
On Deck: Centennial IPA, Dry Irish Stout
P: Cascade Pale Ale
T: Carbed Crystal Light, Root Beer, Vanilla Cream Soda, Tripel IPA, Apfelwein
e^(pi*i) + 1 = 0