Sorry, there is no MC for dummies. I could have used such a book my self
There is currently no way of routing the sound of other apps to JRiver as I know of. There have has been mentioned a sound driver for JRiver, but I do not know if we will ever see one.
Lyrics. I was playing with this some time ago, but I abandoned the project at some point. There is some display view plugins that can be downloaded and modified. Search the 3'rd party plugins forum. there should be a JRiver download page for this stuff. Some of this plugins supports lyrics. The problems is scrolling of lyrics. I found no good solution of this, and the crowd did not go wild when I came with a few suggestions for those features. What I would advice you is to use configure the "Info" list to check out the lyrics while playing. It's an alternative to Playing now, found on the primary roller left of playing now. You can configure this under options, to include Lyrics. This way you can select lyrics in the Info view, and scroll the lyrics manually if it's to huge for the current view. Go to Tools - Options - Theater View - Customize File Info Panel - Select audio template and add Lyrics field as "show only in large view".
That's all I can give you now I'm afraid. Not all what you hoped for, but it's a start perhaps.