New Member Question regarding SeaBlue Pools

Hey Guys, new member here. I'm considering purchasing a 20 x 40 Inground steel frame vinyl liner pool from a SeaBlue pool dealer. Anybody have experience with this pool manufacturer or brand? Looking for feedback on the quality/durability.

I have so many questions about the purchase and would love some of your advice:

What pump size should I be looking at (20 x 40 Cypress with average 6 ft depth)?
What brand of pool equip is good? What should I stay away from? Dealer is specing Pentair equip.
How much should I expect to be able to negotiate on cost with the dealer?
etc, etc, etc.....

Love the website and forum and have learned so much already. Look forward to any help you guys can provide before I pull the trigger on the purchase.