The RP (representative products) node currently only has the representative product of synthetic turf, so unless you do not model synthetic turf, you will not need this representative product.
The SDP (small data providers) node only contains 3 data sets so far.
These two nodes are not really part of the "EF 3.1 background database". They are meant to be filled over time with more and more RPs and more SDP data, but nearly nothing happens there. Unfortunately it is not really in use because EF studies and sharing of EF data is still quite scarce.
You can anytime download the data sets there and directly import them into the EF 3.1 database from Nexus. It is not needed to include them in the default background database. In principle, these nodes are meant to be dynamic and are supposed to be changed/filled over time.