You need to alter your boot.ini
Follow this,
Right click on My Computer, and select Properties. Now click on the Advanced tab. In a section labeled Startup and Recovery click on the button labeled Settings.
You can see the Boot options as you see after restart.
Click on Edit. The info will be opened in Notepad.
Delete the line which says Windows 7 and save it. You can also change the timeout value that is the first line Time to display list of Operating systems to 5 seconds.
Click Ok and restart and check.
I am not able to understand your second query!!!
There is another alternate way to do the above steps. That is to fix the boot. If you have the XP CD, then you can do it. If needed, will let you know the steps to it.
You can use the alternate method, only when the first steps doesnt work.