Garmin Nuvi 350 Traffic: GTM 10 Or GTM 12?

I have a used Garmin Nuvi 350 that I bought this spring. I was looking at the Garmin website and it lists the GTM 10 FM Traffic Message Channel (TMC) traffic receiver as being compatible. However, the online manual refers to the GTM 12 traffic receiver. Can either one of these be used? Or is this an issue where the GTM 10 was replaced by the GTM 12? Also, I gather that a subscription needs to be purchased for this. Can anybody suggest a good website that helps put this all in perspective for me? Although I have been a member of POI Forums for quite some time, until now I really have never had a need or much interest in traffic, but now that I work in downtown Minneapolis, I am interested in learning more about my choices?

Also, I am currently using an Argent Data cable to feed GPS information to my Uniden Home Patrol HP-1, I suspect that only the traffic receiver or the scanner can be used "one at a time" or is there some way to use both devices simultaneously? In the alternative, if I wanted to switch from one to the other, is there any sort of mini USB switch available?

Finally, I do still use my Garminfone and it has traffic on it. Is the source for the data on it the same as the traffic service available with the GTM 10 or GTM 12? Are the newer Garmin Nuvis with traffic getting theirs "free" with commercial advertisements of some sort?

I was also looking through this http://www8.garmin.com/traffic/ and I was wondering if this actually does list ALL traffic services they have ever offered are these just the most current ones being offered?