Have fun reading & such but, "where to begin the knowledge quest?" = In person with other airgunners and hit an airgun store. Someone 3.5 hr from you posted, likely very well worth the drive to share & learn if everyone is willing.
Air in CDA, yes. If using an scba DO make sure you can get a Full 4,500psi fill.
You background will help greatly in shooting (if you get the right gear).
Not a thing going lower budget to start, actually many reasons to do so. This week you could get a Walnut Marauder w/adjustable cheek for $380 NIB. NOT the latest greatest - whic hyou do not actually need-. The 6oz (with 5 minutes work) two stage trigger -a mirror of the Theoben trigger- makes it worth it to me, now that was i the .25 cal only but firearm folks seem to like to go that way sometime. Still plenty of "adjustments" and the 1st airgun to offer such, 5 year warranty, LOW cost poarts w/$5.00 shipping if needed but you wont need as Ace had the orings and everything is so simple But applies to all airguns. A Great starter you may well want to keep.
Raw is a great make, true heirloom quality and some will say heavy. Personally would have Martin in TN build one to my sepcs & preferences. And still well under the latest greatest prices.
Do you think Colville is a long drive?
It's not :
https://www.airgunnation.com/thread...n-retailer-in-colville-wa-today-pics.1300031/ and keep in ind I take crummy pics & write poorly. Indoor test range for Customers (buying) but they are happy to have to punt finger prints on everything -hint do Not buy the umarex hammer they will had you, not The best airgun perhaps-
Nothing fancy here, at all. Heck some need work but... 20 miles short of Colville I do have an scba you could at least see (the colville store will fill) and a bosster I fill that with. The darn gauntlet never seems to fail, AirForce Escape (purchased only due to concerns of the .22rf ricocheting) is Light & not bad at all for it's purpose. The misses had a 20+ year old AA410 that never changes zero and has need on o-ring ever (perhaps something to keep in mind for you?). Benjamin Maximus with mods, the DAQ .452 pistol is fun for 1-2 shots anyway. And I'm sure a few under the bed.
Find some folks with airgun experience and get together with them.
Then shop.
And, do NOT fall in love with the 1st one. Too many excellent choices.
Keep us posted.
John