imac restart sound, stacks and another misc issue (new user need help, i searched!

basically, ive got 3 issues! brand new mac user though, so take it easy on the tech stuff, but im willing to try anything ^^

just for reference, i have a 24" imac which i bought 2 months ago

first of all - today i upgraded to 10.5.8 through the software update thing, and i had some issues with my wireless, that it kept sort of going on and off.. turns out it was something to do with the channels over which my router was connecting to the mac with, which is what apple support told me. any way while i was talking to the guy from apple, he told me to go to my mac HD and pull out a folder called SystemConfiguration and put it on my desktop, i cant remember what where exactly it was from (hope this makes sense).. now the issue is ^^ ive now got this folder sitting on my desktop, and im wondering what to do with it.. is it like a system 32 kind of thing? or can i just drag it to the trash?

second - everytime i restart my mac, it tends to make this loud noise, nothing bad, its just a sound like when you log onto windows.. i was just wondering if there was a way to turn this down? restarting at night is a dangerous thing for me considering how loud it is :S

third - ive just worked out how to use stacks (nifty little thing ^^), and ive read online all sorts of ways in which i can change the icon for a particular stack instead of diaplying the icon for the first item, but they still show all sorts of stuff behind, its not just one clear icon! i was wondering if i could just use one image of a folder and then you wouldnt see anything behind the front one?

TIA
sorry about the ramble, hope my english is understandable, not my first langauge ^^

 

thanks a lot for the help guys, i will phone apple tomorrow and ask them about my first issue

thanks for everything, all is good