I now have an mp3/music manager that I can use to encode mp3s while automagically downloading track/artist details AND it saves the info tags correctly!
Rather than fight with RythmBox I tried (at someones recommendation) another system called Banshee. Seems to do everything I want wight now, though it did take a bit of tweaking to get it behaving as I want. So that's my music sorted.
The plan originally was to use mp3s for compatability with car stereo, so got a fistful of USB thumbsticks for that. Oddly Banshee doesn't seem to pick up the drive when I plugin it in. I had expected it to appear as a device the same as my Nokia phone did when I plugged that in and Rhythmbox was running (not tried phone yet with Banshee). I could then use drag/drop to write to the drive.
Select the tracks in the trak listing ctrl-c, and ctrl-p into USB drive open in a file explorer window. That seems to work.
The first time I tried this approach it didn't quite work. With Windows, once the 'copying files' dialog had gone I could pull the USB drive and it would be fine. Seems with Linux if I don't explicitly unmount the drive (in one of the file explorer menus) it doesn't complete the file write properly so I cannot use the files that had apparently been written to the device.
A recent system update has now caused a warning dialog to open after writing files though reminding me I need to unmount properly before unplugging the device. That will be useful for peeps like me moving to Linuxas a full-time desktop solution from 'doze.