Room Size (%): Sets the size of the simulated room. 0% is like a closet, 100% is like a huge cathedral or large auditorium. A high value will simulate the reverberation effect of a large room and a low value will simulate the effect of a small room.
Reverberance (%): Sets the length of the reverberation tail. This determines how long the reverberation continues for after the original sound being reverbed comes to an end, and so simulates the “liveliness” of the room acoustics. For any given reverberance value, the tail will be greater for larger room sizes.
I can’t answer your specific questions, but I really don’t think the answers would help you anyway… There are a LOT more variables and two different rooms with the same size & reverb times are not going to sound the same.
The real questions should be can you get a sound you like, and it shouldn’t take too much experimentation to figure that out.
You can get lots of reverbs and they all sound different (even with the same basic settings). And of course, some reverbs will have different settings or more controls/settings.
There are also two different approaches to digital reverb. Algorithmic reverb is the most common and it uses math & algorithms to simulate room reverb (or to create something that doesn’t necessarily sound like a real room).
Then there are impulse response reverbs where someone makes an impulse (like a gunshot) in a real concert hall and records it. You feed the impulse into your reverb to simulate that particular room.
The problem now is that it is quite fiddly to get it right - you have to make the settings, test - and then Undo and try again if it’s not quite right.
We’re hoping in 2.0.7 to be able to make this easier by having real-time adjustment of effects like Reverb which should make tuning it to get what you want. I saw a demo of this in early stages development at our recent Audacity Unconference AU14 in Preston - and it looked impressive.