No, the green pad will be fine (but there is no reason why you could not use the SRP with the softer blue pad, going with the least abrasive option first) - I've used the green pad with great success. But if you are in doubt, see if you can get a spare body panel to practice on, to get to grips with the PC.
The more you use the PC, the more comfortable and better you will become with it.
On a side note, I thought the orange pad would take paint off it was so hard, but I used it on my Dad's car recently with Meg's #80 and the paint came up a treat.
With regards to waxing, I prefer to do this my hand and apply with the Meg's yellow round sponges, as I find that Carnauba waxes gum up the pad too much.....
Ps, was there a leaflet inside the Sonus pad box, this was very useful as it describes whay and how each pad should be used and with what products :up