Whats the recommended sample / bit - rate to get the best performance out of the Daisy for something like a looper?
Just start with default settings 48kHz SR / 48 samples buffer and see if that requires any changing
How high is the latency of the Daisy Seed without any processing. e.g. copying input to output with the lowest usable block size?
There have been done some latency measurements with an oscilloscope.
How much memory can I actually allocate and use for a ringbuffer?
For continuous ring buffer of maximum size you will want to use SDRAM (64Mb)
Can i dump the content of a ring-buffer to flash memory for later use?
There’s 8Mb QSPI flash that could be used to store samples. But it’s smaller than total available SDRAM size as you see. In case of Daisy Patch, you could store data on SD card, so maybe you could add SD card reader to whatever you’re working on and reuse existing code.
Is it possible to access the memory of the Daisy Seed via USB?
There’s no readily available code for this. I don’t even understand what exactly you’re asking for here. Something like a block device with virtual filesystem? This is technically possible, but I don’t think it would be provided by Daisy itself any time soon.