This is intended to be connected to the female pipe threads of an inline valve.
Haven't seen them listed separately, but anyplace that sells o-rings should be able to provide one (Autozone, True Value, Ace, etc). Take the lid with you. You may have to purchase a couple of different sizes if they're close, but they're fairly inexpensive.
The regulator has a permeable white dot that is designed to relieve excess pressure by slowly releasing water droplets. there must be back presure on your sprinkler drip system
Yes, absolutely. You may have to play around with the run-times, but will definitely work.
I Installed this vertically and it worked great. No issue so far.
It is part of the design that should not affect what you're seeing. Rain Bird has a policy of 100% satisfaction. For assistance you can contact them at 1-800-RAIN-BIRD
This unit is limited to 5 gpm. Rain Bird has a 40 psi filter with a 1" inlet that can handle up to 15 gpm. Model is PRF-10040SX/
Yes, but it should be installed in a box so that you can remove the strainer for cleaning.
From the RainBird website for this product: "Filter must be installed downstream of any valve; warranty will be void if installed under constant pressure." Seems pretty clear... See https://www.rainbird.com/products/pressure-regulating-filter-rby