Plumbing questions

[Starry]

Im planning out a 25 gallon sump at 300 gph flow for a 33 gallon display tank.
The layout will be intake/skimmer - fuge - return. I haven't measured everything exactly, but have a rough estimate. Hight from sump to tank 5' with 6 90's. Roughly 1.5' horizontal. 1 ball valve for exess flow back to fuge. 1 union for dissassembling.

1: What kind of pvc glue does everyone use?

2: The mag drive pumps have 1/2" outlets and I wanna use 1" pipe. Will reducing the 1" to the 1/2" create a bottleneck and still create the same head pressure as 1/2" pipe?

3: Should I go with the Mag 7, or is there a better option?

Thanks