does the 1810 need extra memory for multiple copies thru the doc feeder????

No it doesn't require additional memory. The 1810 has a 30 sheet feeder. The 1510 has a single sheet feeder.

I'm not sure about page memory limitations off the top of my head, but I've demo'd many of the KM-1810's, and shown 8 originals making 5 sets with standard memory.