Yes, it will work with XP. When you connect the iPhone to your XP computer, it should be recognized as a camera, and the Scanner and Camera wizard should launch.
If it doesnt, go to My Computer, and look to see under your hard drives to see if you can find an iPhone icon under a section called Scanners and Cameras. Double click on the iPhone icon, and you should see all the pictures you took. Copy them off there to your hard drive, and you are set.
Not sure if it can be done. You can just send your pictures from iphone to your email address on your computer then save it on your computer from your email.
When you plug in the phone, it will show up in "explorer" under the c: drive as Apple iphone. Click on that and it will show an internal storage folder and a DCIM folder. The DCIM folder is where your pictures are.
Select all pictures and drag them to a folder on your hard drive and you'll have your pictures from your computer on your hard drive. You can not do this in reverse, you can only take the pictures from the phone and put them on the computer.