VST = "Virtual Studio Technology." It is a standard for writing audio plugins so that any conformant DAW (Digital Audio Workstation) can make use of them. And almost everything out there, including Audacity is VST conformant. The professionals using Pro Tools spend thousands on various effects, and because the VST is an open standard, there is a small army of people out there producing plugins for free, too.
Here's an example.
This is a VST plugin I love called Bittersweet. It is a transient manipulator, which means I can use it to either smooth out transients (say, pick noise on a guitar track) or enhance it (line on the attack of a snare drum) as needed. It is immensely useful, and it costs absolutely nothing.
I can download it and install it, and it is on my computer, not attached to any one program.
If I use Reaper, I can attach it to any track, route the audio from the track to the effect, and listen to the change in real time. Here I have it attached to a ukelele number I'm noodling on. I can turn the dial and push the buttons and monitor the signal just like I could if it were a bit of hardware bolted into a rack.
Now, her is the exact same plugin in Audacity.
Now, the first thing you'll notice is that this doesn't have the nifty interface that it had with Reaper. As long as you understand what each of those inputs means it's not a problem. I don't happen to know what they mean, so for me, that's a problem. I know if I had that nice dial I could just turn it and see how it effected the sound of my track. Some effects have dozens of inputs, though, so the ability to render a nice interface can be important.
What you can't see in the picture is that with Reaper, I can play the track and tweak the effect at the exact same time, just like it was a send effect on a real mixing board. I can even send live signal through it from an instrument or MIDI device just like I could a stomp box or racked effect. Audacity doesn't let you do that. It simply takes a section of track off of the disk and applies the effect to it, then writes it back to disk, so you can't hear what the effect is until you've modified the track. I know it allows you to "sample" it, but it's still kind of cumbersome.
Anyway, the point is that the effect here, Bittersweet, was only on my computer once. If I fire up Cubebase, it will be there, too. (I'd' provide you a screen shot of that but for some reason the plugin only stays visible if Cubebase is the top window.) Tomorrow, if I go buy Pro Tools, I can still use the same Bittersweet install I already have. VST lets you do that.
So you can get a different re-verb than the one you're using. There are, literally, hundreds of reverb effects to choose from.
Here's a place to start...
Oh hey, as far as using the verb on the vocal track, you can do the following to use the verb on the mixer.
You are going to close mic the amp and run the input through the mixer and add reverb there. That's good.
When you are done with that, simply run the vocal through the same signal chain, and pipe it through the mixer using the same reverb settings.
Bass is often recorded like that for players that have a "signature" amp sound. Since it is really hard to record bass live (it bleeds into everything) it is usually recorded DI. After all the other tracks are laid down, the bass signal is ran back through the amp, and that signal is recorded. Works great.
Someday we'll win this thing...