Make a send, pop on what ever you need it to be. In this case a reverb and delay group and after put a compressor that side chains to the lead. Space will appear more after the lead is played. As for compression etc, I suggest first getting all staccato (rhythm) elements playing nice and tight together. See it as a drum circle. After add in your pads/space/reverb and lastly the lead. It will immediately come apparent what you can still do or what you can delete to keep the lead up front.