Hi dust ward,

sample management via USB works fine. So YES to your first question.
I do not have a machinedrum so not sure what “sample warping” means. But OT is very fine for live/realt time looping/sampling/mangling on the fly! Very …
The sampling time does not depend on the size of your memory card. Live sampling uses the internal RAM, its size is fixed.
The manual says:

The total amount of RAM memory available to a project is 85,5 MB. This memory is shared between the track recorders and the samples loaded to the Flex sample slots.

You can do the math: 80 MB for stereo sampling 16 or 24 bit, 44,1 khz