Hey,
No problem, I learn a lot by answering questions. There are only a few Cubase users here...
Yes, the programs. A program contains both the wav data and the sample information, like key assignment, velocity, filters, envelopes, LFO's, amp, pitch, etc.
I don't know if Sampletank can import programs from the MPC. As long as you can export programs in the formats Sampletank can read, you're good to go. You'll have to look it up in the MPC manual.
Cubase has a step sequencer, but only for MIDI. Seeing how an Akai program is in essence a 'synth patch' which you load into a sampler, you interact with it as a MIDI object and not as audio.
What you would do is load an instance of a softsynth/sampler (like Sampletank or Kontakt) into a VSTi track in Cubase, load the Akai program into the softsynth/sampler then write a bunch of MIDI notes into the track which trigger the Akai program. When you hit play on the transport bar, the notes get sent to the softsynth/sampler and they get triggered, just like if you had written notes into a track on the MPC.
When you are done writing the song and want to mix it down to a big audio file, you simply go to File>Export Audio and Cubase 'renders' everything into one file. This file will have your sounds from the Akai program all sequenced...you can then burn this to a cd and listen to it on a cd player.
Take care,
Nick