How to create liquid carbon, and what kinds of properties does it have?
It's possible to create liquid carbon, but it's extremely hard. As you can see on the Carbon phase diagram  if you want to obtain "easely" liquid carbon you must do it at $\ce{1 GPa}$ and $\ce{5000 K}$.

And for the properties I really don't know but carbon follows the octet rule and it might be very reactive as an electrophile because it will just have four electrons around it. 

I hope it can help you a bit, i'm seeking in some data-bases but there are not really things to answer your question. 

Have a nice day.