Which drum VST are you using.
I would use the SI drums as they have more options for different kits.
It is a GM player so if the Band Trax files are GM, which I would think they are, then you should not have to edit the drums they should play using Midi channel 10 the default GM channel.
Here's a way to easily set up a project using a downloaded GM midi file. Sorry if things are a litle different in the version of Home Studio you have but this works in the new version which if you didn't already get one grab it now.
http://forum.cakewalk.com/Sonar-Home-studio-Giveaway-m3718858.aspx First go to your Preferences/ Midi/Devices and uncheck all OUTPUT boxes. Leave the inputs alone.
Now all you need to do is
OPEN any GM midi file and it will load a new project with the TTS_1 set up and ready to play the song. You can OPEN midi files directly if they have been set up to use SONAR as the default program. Or use the FILE/ OPEN and browse to your containment folder. Do not import the file, that won't work. You have to open all midi files or they loose data.
Now you can play the song and start editing.
I then replace all the TTS-1 sounds with better VST instruments like the drums, bass and pianos.
The free version comes with Rapture which is loaded with sounds. That's worth $100 alone.
I've never bought a midi track since they first came out on floppy disks. I've often auditioned the ones you pay for and find they are rarely worth the money. There are many free versions out there and you get lucky sometimes. 80% of them are terrible versions done in something like Band in a Box by someone who is obviously not a musician. But I gleaned about 20 new songs this last year that were well enough done that I used them with a lot of editing involved to bring them up to my standards. I don't think I've ever come across a file that didn't have many errors. Bad notes, tracks not quantizied. Often I just make my own and I must have over 300 midi tracks by now of my own.
Before I get dementia I will someday post these all to my Web site.
Here I did a sample . seems to work. Couldn't post a CWP file, they open as a txt file
http://www.cactusmusic.ca/Docs/crocrock.mid