I like the option of using R/R pairs better than using WSDL because many times most of the elements in the WSDL are defined as optional and the resulting VSI contains values that do not appear very realistic.
Take the VSM generated from WSDL and manually add the Live Invocation step -- should be OK but you have to deal with all of the branching logic. With R/R pairs, you get the luxury of allowing DevTest to create a proper model including the Live Invocation with values that make much more sense.
In terms of learning, I cannot help a great deal in that area.