I am running the OS from a pen drive! Will it perform optimally from a pen drive.
If it's a "Live" USB, then no not really .. it will generally take MUCH longer to boot, and won't mange memory as well.
Also will the changes i make or the stuff i download will be loaded every time i load ubuntu?
It depends on how you installed to the USB stick ..
if it's a "proper" installation .. YES
If it's a LiveUSB .. NO
If it's a LiveUSB with persistence file .. YES
Now that i loaded ubuntu and started exploring it, what should i learn more? I want to be well versed with linux! May even connsider it as a profession. So what can i do in it and where should i start?
Hmm, I suppose it depends by what you intend to do .. but here's a few suggestions/possibilities
a) the way permissions work in Linux
b) the directory structure
c) the way package management works
d) the way drivers are loaded/unloaded
e) the command line and man pages
Maybe check this out:-http://linuxforums.org.uk/index.php?topic=232.0
or check the web for other free resources.