#1
So I'm putting together a bass rig for fun in addition to my guitar setups. Question as far as using multiple cabs with an Orange Bass Terror amp:

I picked up the Orange Bass Terror 500w head. (4 or 8 switchable Ohms, 2 speaker outs)

I'm thinking about getting this used Sunn 1x15 cab off Craigslist that is 300w at 8 Ohms.

Was also going to get an Ampeg 4x10 in future, would I just run the amp at 8 ohms, and use the speaker outs as usual to run them both? Or would I have to do some sort of bridging or something? I'm entirely ignorant to Ohms/Bridging, I just plug the 16Ohm out into the 16Ohm ins on all my cabs.

I've also heard that with bass amps/cabs you don't have to match the Ohms, you can have either the cab at a higher impedance than the amp, or the other way around and it's fine. Truth? Seems wrong to me.

(By any chance would anyone know if $300 is a good price for that Sunn cab, it's in really good condition with dust cover & casters)

Thanks everyone!
Guitars:
Epi Les Paul Custom Blackback
Gibson SG Classic w/ P90s
Epi Les Paul Ultra I
Squier Tele Black & Chrome
Taylor 210e

Amps:
Marshall JVM210H
Orange Tiny Terror
Marshall 1969 Lead cab
Orange PPC 2x12 cab
#2
It depends on what impedance the other cab is. If it was 8 ohm you'd run the amp at 4 ohms because you'd have two 8 ohm loads in parallel. The formula is:

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