[RTTY] TS 590s on RTTY

[Dave Barr]

I am planning to help a local ham get his TS 590S on digital.  I haven't 
seen the rig yet, but have looked at the manual on line, which seems 
Kenwoodishly lacking the needed details.  My questions:

Can the rig run RTTY with only a usp-usp cable between the rig and 
computer, which the manual hints at?
Is TS 590 FSK true FSK or is it internally generated AFSK?
If AFSK is desired, must it be run through the 13pin din connection?
Are all filters available in all modes?
I prefer not using interfaces, other than small transformer-isolation 
boards and ptt connection.

Thanks for any advice.  I have been spoiled by my K3.

73, Dave, K2YG