No. Apple does not allow hard drives to be connected at this time.

I can't say with 100% guarantee (yet), but since Apple explicitly mentioned the possibility of connecting an SD card at the keynote, I assume so. The decisive factor is that external memory is supported, which media exactly is still a question of the output voltage...but since the iPad Pro can also be used as a PowerBank, that is also guaranteed ;-). Conclusion: The probability is high. I will be able to say for sure in a week's time.