Will my iCloud photos fill up my new iOS device too?

Hi. I'm new to this so I hope I make my question clear. I have had an iPod touch 5th generation since Christmas 2012. Since then, I have been sent requests to join many photo streams from my family and friends. Because of this, my iCloud is now extremely close to full, meaning that soon I won't be able to receive any more photos. Today, I am getting an iPad mini, due to my iPod being no longer sufficient for my needs. I want my iPad to be created with my same Apple ID, and have access to my app/song/book purchases. Firstly - can I do this and choose what copies over, or will the contents of my iPod and iPad have to be exactly the same? I want the option to copy my purchases over if I want. (My iPod is full so I don't want to copy everything and fill up my iPad immediately, too (they are both the same amount of storage). Secondly - if I sign into my new iPad with the same Apple ID that I used for my iPod, will the contents of iCloud have to copy over too? My ideal for this situation is to have the choice to copy content from my iPod across, and not be in the situation of "it's all or nothing". I hope this makes sense and would really appreciate some quick responses. Thanks for reading.