Multi-track audio plugin: VST or Premiere SDK?

Thanks to Bruce and the other posters in the forum, I'm new to Premiere plugins but there is a lot of helpful information here.

The Setup

I'm writing a plugin that is basically an adaptive mixer - it takes inputs from two separate audio tracks and performs frequency-domain manipulations on them. I'm trying to figure out if I can write a VST plugin (for more information see here and here) that interacts with two audio tracks in Premiere. The process would be

1. Select a region of time
2. Apply the plugin to a target track over that region
3. In the configuration UI select other track(s) as input to the effect
4. The effect runs, using the audio samples from the target track and input tracks, to generate an output
5. This output becomes the target track over that time region

Ideally the time window could be shifted, which would maintain all parameters but just shift the region that's being processed.

Questions

1. Is this possible with Premiere's implementation of VST? Can a VST plugin take more than one track as input in Premiere?
2. Regardless of the answer to #1, would you advise creating this plugin using (a) the VST interface, (2) the Premiere SDK, or (3) the After Effects SDK?

Thanks for any insight, between reading the VST standards, the Premiere SDK docs, and the After Effects SDK docs I'm feeling a little lost.

-Bryan