Re: OS 32bit or 64bit
Certain intensive calculations such as video encoding, work somewhat faster on 64-bit. You can also natively handle 4GiB of RAM or more on 64-bit.
Of course, 64-bit operating systems only work on 64-bit CPUs. Look up your CPU on Wikipedia and it will say if it is 64-bit or not. Most in the last six years are.
You would have to reinstall Ubuntu to get 64-bit; not worth it in my opinion, just install 64-bit the next time you do a clean install of Ubuntu.
I try to treat the cause, not the symptom. I avoid the terminal in instructions, unless it's easier or necessary. My instructions will work within the Ubuntu system, instead of breaking or subverting it. Those are the three guarantees to the helpee.