I currently use just one saddle .. Stubben VSG... an old school one at that. Darn thing is older (and prettier) than I am. It is my go to saddle over fences. As long as it continues to fit my beast I'll never part with it.
I'm moving up to Novice and am finding the need for a dressage saddle more and more. My current saddle doesn't work as well with a long leg and I have issues not reverting back to my old Hunter habits with my seat.
As far as bridles... if you need more than one bit, it will be so much easier if you have separate bridles. If you can't afford separate bridles, go for one that has a buckle rather than a screw or the hook thingy so it's easy to change out. Nothing like trying to change a bit out with sweaty hands.
If your horse says no, you either asked the wrong question or asked the question wrong
And God took a handful of southerly wind, blew His breath over it and created the horse