Have you taken a look at this in addition to the links you provided? (
https://bitcoin.org/en/developer-examples#regtest-mode) As you mentioned both regtest and testnet, do you know which you are going to use?
Depending on what the experiments are and whether you are using regtest or testnet, you may not need much in the way of requirements for with regtest or testnet itself. It is difficult to give server advice without knowing a bit more, such as what you are looking at experimenting with, OS to be used (Linux/Windows/Mac...), which way you are going to do the testing etc. But probably 2GB of RAM would be sufficient and 4GB RAM should be fine. Nothing high end for 2016. I doubt it would be a special case, no.