Is there a way to get Foobar2000 to automatically scan a group of files & automatically insert correct Total Tracks & Total Discs tags into files which already have the Track Number & Disc Number tags in said files? I take it an easy way would be to get Foobar2000 to tag the totals from the maximum values it finds (BTW, any of these values wouldn't make sense with a value like '04' as opposed to '4', so would the solution cover that as well)?

If the albums are stored in seperate directories i.e. Album A is in a different directory than Album B, you can use the "Auto Track number" in the Properties dialog box (right click anywhere in the dialog box to get a context menu).

Auto track number will also remove padding automatically (i.e. 4 instead of 04)