The DC Commander uses the standard R4LC smoke output, so it has a 4A triac. Note that it's only 4A with proper heatsinking, but it'll handle a standard Lionel smoke unit with no problem. I figure that around 5.-.6 amps maximum through that triac with no heatsink. I've powered the PS/1 smoke unit with the R4LC without issue, you should be good.
Of course, you know that I just have to put in a plug for my Chuff-Generator as opposed to the old Magnet, right? 
I have used the entire tender on a couple of brass locomotives that had the trucks isolated. I isolated the drawbar (one I made of fiberglass stock) and the coupler mount and just connected to the tender.
I buy my nylon screws from Micro Fasterners, they have them in both metric and SAE sizes. I just stocked up on a number of sizes, the small ones for brass, the metric ones for Lionel tenders, and the SAE ones for MTH tenders.
