Hi Andre,
I do not conduct any training either for RFI's and RFP's. I must say I have a support group that takes care of Ariba Buyer Support, and I incorporated Sourcing in there training. They take technical calls for sourcing events also.
Honestly, we do not receive very many calls when we publish RFI's and RFP's. But to your point, I keep my templates simple, and it's pretty much self explanantory.
I also send the suppliers an invite email, describing how to login and where to find help if they require it. I refer them to the Ariba tutorials available in the Help.
As for auctions, I do conduct online practice sessions with all the invited suppliers 2 or 3 days prior to the actual auction, This permits the supplier familiarize with the auction GUI and the options available to them. In the opractice event, I incorporate all the established rules that have been built in the real auction, so on auction day, there is no suprises. I find conducting a Practice auction (ususaly lasts 1 hour) works quite well.