I can answer the last question--UC Davis USDA germplasm has persimmon scionwood.

Carla in Sac

Here is a link that might be useful: UC Davis scionwood

Ralph, the larger the better but 1/4" is probably the minimum. They will hopefully be big enough for grafting next spring. You can get scionwood of several varieties from England's Orchard. The USDA service should only be used for varieties you cannot get elsewhere and it ends up being more expensive after you have paid for the shipping (the wood is free).

Scott

Most that I use as rootstocks are 2-3 years old - but I don't 'push' with any fertilization. Suppose you might be able to get some up to decent caliper if you fed 'em a little.
I did graft some 1-yr container grown ones earlier this month - but the scionwood was tiny little stuff.

I do a simple bark graft - but have done simple whip and whip and tongue - all with good success. Persimmons are really no more difficult or finicky to graft than pomefruits - but require much more in aftercare - you've got to be very diligent to keep shoots from below the graft rubbed off, or they'll quickly overtake the graft, it will decline, and die out.