iMac 2011 w/CS4 Adobe software wants to connect with Mac Mini?

Is it possible to do this:

• Keep my iMac 2011 { CS4 Adobe software} to use it as a display and use this software?

• Get a mini mac to run a newer operating system and internet?

I can't run a newer osx on my iMac because of the CS4, but the iMac runs well. So I want to have internet access to run my Etsy and eBay and internet stuff in general.

I wonder if using a USB plug to transport my photos from iMac to Mini would work. This means I would not use my iMac for any internet stuff.

I suppose this is a messy idea, what do you all think? Could really use some clear, smart thoughts.

Thanks in advance for whatever help you can give.