You've got a couple of options with the thorny vine. You can dig it out and hope that it won't regrow from the roots, or you can kill it with brush killer prior to digging it out. To use brush killer, cut out the vine and dab undiluted brush killer (similar to Roundup but stronger on woody plants) onto the cut ends. Then give the brush killer several weeks to work before removing the rest of the plant. You've also got a couple of options with yor roses and perennial onions. You can leave them in place and work around them or dig them up and set them aside while you prepare the soil. If you dig them up, slip them into pots in a shady spot while you work. Try to get them replanted as soon as possible to ease their shock. You can prune the rose before transplanting so that it'll be easier to handle. Preparing the soil is a big job, but your plants will reward you for a job well done.