You should be able to boot gparted on a thumb drive. Many computers dont boot usb drives like my dell computer. However, burning the iso version of gparted on a cd is probably easier and will work on most computers.
Second question:
Software does not install like in windows. The installed files are put in different directories according to file type. For example, executables are put in /usr/bin or /usr/local/bin. Man pages are put in /usr/man. Startup files are put in /etc/rc.d for slackware. etc...
So it does not really matter where the source is located. It only matters which partition your directories are located.
FYI Before you make the ntfs partition smaller, make sure you defrag windows at least three times.
When you enlarge the linux partition, I am not sure about grub, but with lilo bootloader you will need to use a live cd and the chroot command to enable the linux partition reboot. See this link for help.
http://www.linuxquestions.org/questi...ghlight=chroot