Hello,
Thank you for your message, I can provide you some general information which hopefully helps you to make the decision.

As you want a multi-purpose system and your room is also large enough to handle many type of models, I would recommend going as large model as your budget allows. I know it sounds like a typical sales speech, but unfortunately it's the best way to go. If you can listen and compare different models, for example 6010A, 8020B and 8030A next to each other in the same room, you will notice that you will get a better sound quality with larger models. Also bass extension and maximum SPL capability are one of the variables that will get better as you go up in the model range.
The subwoofer (notice that you don't automatically need a subwoofer) you should buy depends on the speakers because we want to have a balanced system, i.e. so that the maximum SPL of both units are fairly similar. You can find our recommendations for different speaker/sat combinations from our homepage
http://www.genelec.com/learning-center/ ... selection/ For example if you are having a multichannel system of 8030A speakers, the correct subwoofer would be 7060B. Notice that the bigger speakers you get, the more bass extension you have, which means that the need for a separate subwoofer gets smaller.
Since you want to use the system with multiple sources, you need a device which you use to control that. I would recommend getting a typical consumer type AV receiver which you can found from multiple manufacturers like Yamaha, Onkyo, Pioneer, Marantz etc. Even the fairly affordable models are sufficient for this purpose as long as they have connections for active speaker, more specifically called pre amp outputs. You should ask advice from the sales person in the shop if you are not sure which model has them and which doesn't.