Unfortunately, unless you use some kind of profiler, multiple devices are not supported.
I'm using a set of CH controllers (Fighterstick, Pro Throttle and Pro Pedals), the only way I could enable them all was to map all of them to a single device (CH stuff comes with a nice profiler for them, but unfortunately, it doesn't work with anything but CH controllers). A fix for this has been requested on SCP forums (by numerous people), but it doesn't seem to be easy to implement and thus, not coming anytime soon.
As for TrackIR, you may need a special DLL file for it to work, though I don't know for sure, since I don't use it.