As part of the escrow protocol each involved party has to share things like public keys, transaction ids, signed transactions,.. with each other via a secure communication channel.
For testing we can just share those things via messenger and enter them in textboxes but that won't be very convenient or secure :p
Is communication between the parties something I don't have to worry about?
Correct.
As long as the basic functions are in place allowing us to send to multi-sig, verify multi-sig, and vote to release multi-sig, then all other communication should be handled inside OT as part of the bailment protocol.