For the size of the rack and the amount you're spending... your results are going to be very limited. Ambient requires lots of subtle (blatant?) changes over time. That means multiple sources of modulation. That will require a lot of purchasing if you're looking for something that is generative (hands-off) in nature.
Your CV pal has two gate and two CV outs. That's going to leave you wanting. If it's capable of using one of those gate outputs as a clock a hardware sequencer locked to the clock would be helpful. Problem is that if one gate is used for clock... you probably want some way of resetting your modules....
Restarting LFOs, envelope generators, and sequencers yields more predictable results... even if you're only retriggering things on the first downbeat.
The Batumi is only half complete without the Poti expander. Get it.
Do you need to timestretch samples in real time? If not, then just use Ableton to get your samples to the right length then export them. Speaking of... if you can do without the time stretching then 1010Music's BitBox is a good choice. It also has two alternative firmwares that you can load giving you a complex digital oscillator or a multi-effects box.