I’ve only got 2002 so this may not be the same. On your first point – Word can print pages 2-up, but so too can many printers – the settings cause different things to happen.
On my version (2002) if Word is asked to print reversed AND asked to print 2-up it refuses – knowing it cannot. Your printer (if set independently of Word) would of course not know, and simply print as you describe. So – in 2003 if Word allows you to select two-up I’d expect it to work
To set it in Word (rather than the printer) click File > Page Setup > Margins > Multiple Pages > 2 pages per sheet.
If that doesn’t work, a macro could probably do the reverse printing “relatively” simply – I investigated telling a print command to simply print pages 99,100,97,98 …1,2 but suddenly realised that this was dependent on whether the total number of pages was odd or even, and there was a string limit of 256 for the page spec. Nothing insurmountable – but only required if the above doesn’t work
On your second question
The page numbering looks tricky – you could fudge it with a footer for EVEN pages, and simply print the number as far to the left as you could get.