Yes it is the 990 command set that you need, I believe Gromet made a mistake. 993 is the expansion set, basically just an extra remote.
Try Charles Ro at the link bigdodgetrain posted above, if your not familiar they are a very reputable dealer. I'd probably call them to order and verify the command set is in stock, however,their website is usually up to date.
Your old transformer will work, but as mentioned above a more modern transformer like one of the 180w bricks has better protection for your electronics with its modern breaker.
The new ZW-L is a huge transformer with a huge price tag, probably way more than you need.
