Cant help much but as no one else has responded I thought you may be feeling lonely.
Firstly the DVD+R DVD-R debate.. there is still no indication which way it will go but now that Microsoft have come down in favour of DVD+R this might tip the balance. There are now a number of external DVD-RW drives that support both DVD+R and DVD-R so if you want to hedge your bets then go for one of these. Note that DVD+R media is more expensive than DVD-R but not much.
Secondly if you have USB 1 then go for Firewire input. If you have USB 2 then either Firewire or USB should be ok as their throughput is roughly the same.
Good luck with it.