For bush type squash, like yellow and zucchini - I would recommend that you place each plant next year in the middle of a 3ft by 3ft square. Also, there is a thread on here somewhere - where SNIBB has put some photos of growing these types of squash vertically. You should check it out, it's a great setup. My yellow squash have taken over my peppers as well, so - I know what you are dealing with. Next year, i'll be better prepared for the squash.

This year I also tied my summer squash to a stake and it works fairly well, if you can keep up with tying up the plant. I wouldn't really say they take up much less space but they are easier to pick and I like to think less prone to disease with the leaves up off the ground. The vining squash do not require staking if you give them a support they would gladly climb it.

8 feet is only the beginning for your vining varieties, they will easily make it to 25 feet or more. You could try putting a short fence between the peppers and the pumpkins but you will still need to make sure they don't climb over the fence.

Moving the vines is fine and won't harm the plant. And cutting the leaves off is not ideal but it won't kill the plant unless you cut most of them off.

In the future be sure to give your squash enough space. You will quickly find out just how much space that is. If you want to plant other crops close to your squash be sure they are tall plants, short ones will be easily overtaken.