Computer Switch, Working With An External HD, & Restoring Preference Questions

I recently bought a MacBook, and before I sold my eMac, I bootable copy on my external. I got a few questions.

(1)How is it working with an external? Inconvineint? Easy? I plan on getting a bigger HD later on but for now I'll deal with the 60 Gigs.

(2)When I start working with the external can it go to sleep or anything? Like where would I find preferences to that? Do I have to get somekind of software or sumthin? Cause when I turn it on it just stays on.

(3)How do I get my preferences and bookmarks from my other applications? I use Shiira as a browser and I can't seem to find the bookmarks I had on the external. I don't really know where to look. Unless there isn't a file for that. (4)If I open an application from my external, like say Shiira, shouldn't it have all my bookmarks there? When I open it from my external I just get the icon in my dock, that's it. Can't even open a window.

(5)Since I backed up my whole HD, and I don't plan on keeping everything to save space, is there anything that I should probably keep but don't know about. I know I want to keep music and pictures and stuff, but what about like the stuff in "library" and "system" Do I need that stuff? I don't plan on using it as a bootable drive.

Thanks guys!