[SOLVED] How to start Gparted Live on a USB from Xubuntu on Mac 3.1

Installed Xubuntu 14.04.3 desktop version on a newly installed SSD on a Macbook 3.1. (Trim was installed through Mac earlier, before I replaced the Hitachi drive ), Only the 32bit Xubuntu OS version was recognized but this is fine with me.

Studied all the instructions relating to the installation for this model MacBook. Created a 100MB /boot/efi partition as demanded by the installation, (formatted as FAT32), and selected GPT as the partition table. In the end I didn't have to go through any special re-configuration after installation. Xubuntu boots, (fast) reboots and shuts down without any problems and all the installed software functions perfectly well.

However, I wasn't comfortable that everything went so smoothly, and wanted to understand what I did, so ran Boot repair from within Xubuntu and these are the results: http://paste.ubuntu.com/14364911/

My concern is with this line: WARNING: GPT (GUID Partition Table) detected on '/dev/sda'! The util fdisk doesn't support GPT. Use GNU Parted.

Also, I have no clue when installing CPU or System related software, whether to choose 32bit or 64bit?

Finally, created a GParted live USB key but I have no idea which keys do I use to select the USB on boot.

Thanks in advance for any replies that would help me move on.