Hi Jim
I have a KMA as well as the Pa600. The answer to your question as to the sound editing is yes you can.
1: press the program button, top left.
2: select the sound, right hand buttons
3: Press the menu button top left hand of screen
This gives you access to all the editing facilities.
The SD card is a standard size I use a 16GB sandisk
I don't usually edit the sounds apart from tweaking the EQ and effects so I can't help you much there.
PM me if you need any more help, I'll do my best.
The Korg OS is great when you get to know it, but it is a fairly steep learning curve. I've been a korgy for 10 years or so.
Regards
best of luck
Col