I have the external version of the drive you are considering - the DRX-500UL and its excellent. I'd recommend that you do a firmware upgrade from the sony site before writing discs as I had a lot of coasters until I did this!

My standalone dvd player recognises DVD-R and DVD+RW and thats all I have tried so it may work with others.

DVD+R is the newest format out, so for compatibility DVD-R is the best at the moment for standalone players that I have found.

You don't need different software for each format - Nero will automatically recognise the media. I'd go for DVD-R as these are the cheapest I have found and have no advantage over +R (that I can tell) , but if you want to packet-write I'd go for +RW over -RW. The RW discs are dearer though.

Hope this answers some of your questions!