Art;
Since no one has jumped in yet, I'll offer a few comments.
First, not sure why you want to run DCS in passive mode?
DCS and Legacy will play well together, with the Legacy base cabled to the TIU using the MTH cable.
Each TIU channel will handle 10 amps or 180 watts of power. This is enough to run several trains on each, or at least two long passenger train with incandescent lighting.
You could easily run your lower level on one fixed TIU channel and the upper on the second fixed channel. Observe the 250 feet track limit per channel.
You should observe the star wiring guidelines using a distribution block for each channel. You should also observe the 10-12 track pieces per power feed, and no more than 10-12 feeds per channel/distribution block.
On my layout the common outside rail returns are all buss wired, and it seems to work just fine.
I power 400 feet of track total using all 4 TIU channels and magic bulbs with an older rev I3a TIU. The two variable channels are set to fixed. I get mostly 10's, with an occasional 8-9. I use lighted bumpers at the end of several sidings where the signal previously was poor.
Hope that helps,
Rod
