Falls at almost the first hurdle for me. Your friend describes how to compress something and describes a process based entirely on meter read-outs what is IMHO entirely the wrong approach. It's your ears that count in every circumstance and doing anything simply by achieving certain meter...
A basic audio interface can do what you want, starting (bottom end of market, but NOT IMHO bottom end of the specs or performance) with the U-Phoria 204 (the cheaper 202 doesn't have the monitor mix control you want).
Maybe I've misunderstood your needs, but a mixer seems to be overkill if all...
Audacity is very basic, really an editing software rather than a DAW.
Reaper is very cheap and it allows you to try it (without limitations) for as long as you want free of charge.
I'd recommend going down that route and check out the video suggested above.
ALL DAWs require an amount of...
I think we are on a hardware system, Tascam or the like. And the track indicator box on the built in tiny monitor which, according the poster shoukld show a dot or a line to indicate empty space.
I'm just guessing but that seems the obvious answer (very obvious ) from what he writes.
Of...
PLEASE, PLEASE. I hate saying this, but the poster who said a lack of dynamic range is "good" is wrong. It's neither good nor bad. And I say that with the greatest respect to Steen.
Dynamic range IS - potentially - a stylistic choice while mixing and mastering, but normally it is good to have...
The forum's set up so you have to wait to make a certain number of posts before you can post a link. Not sure how many, but someone will surely stop by and let you know. Meantime, I'd start reading some threads that interest you and joining in.