I'm looking into getting a toggle switch to hook up my track and then also a DC power pack and DCC command station so I can switch the layout between DC and DCC. I'm a bit unsure about which kind of toggle switch I need (SPST, DPDT, etc.) for this situation. Anyone know?
A plain old double pole, double throw, center off toggle switch will do the job just fine. Wire the DCC to one side of the switch, wire the DC to the other side of the switch, then wire the track to the center posts on the switch.
If you have more than one insulated loop on your layout, you can use an additional toggle switch for each one. For instance, our N-Trak club's layout has three lines - the Outer Main, the Inner Main, and the Branch Line. We have 3 toggle switches in our control panel to select DC or DCC power for the 3 lines. I have the exact same set up on my N-scale home layout, also. Both me and my club have had this set up for 10 to 15 years or so now, and never had a problem.
You just have to exercise some caution not leave a DC loco sitting on a track while powering up with DCC. And it's not the end of the world if you do. It's happened to both me and our club members at one time or another. A DC loco will make an audible 'buzzing' sound if exposed to DCC current. That's the motor trying to reverse direction 60 times a second. If you hear a buzzing sound after turning on DCC, simply turn it off, or locate the buzzing locomotive and remove it from the track. It's not going to burn up right away, but it will start to warm up as minutes go past, until it does burn out a winding. And while all of the cautions posted by others are viable and are items to watch for and keep in mind, they are fairly over-hyped in my opinion.
Once again, a simple DPDTCO electrical toggle switch will do the job just fine. There's really nothing to worry about, as both my club and I can attest to.

