Re: Trek shops. I don't mind them in principle - why would another bike shop be a problem? It's that they're edging out multi-brand stores that carry non Trek, non Bontrager branded items. Not to mention that these multi-brand stores are usually mom and pops or locally owned chains.
A Trek store will probably carry a Trek/Bontrager stem that would fit your bike, so you could still give that a shot. Has this thread determined if you have a fat (31.6mm, I think?) bar, or a skinny (25.4mm) handlebar? I'm not sure when road bikes went fat bar, but my 2004 Bianchi is skinny, and my 2019 Lynskey is fat - so no help from me.
As for saddles - any shop, even a Trek shop, that will allow you to fit a saddle on and take it out for a ride (even with a deposit) - would be good.
Of course, there might be people who will look at you funny for having Bontrager parts on a CAAD - but ride what works!