My First Mac!!!

Right now I am typing on my first mac, a 12" iBook that I purchased from Xephian. I still have to get used to the operating system after using windows for my entire life. A few easy stupid questions:

I like Firefox browser so I went to the website and downloaded the mac version and then Safari gave me the warning this a program are you sure that you want to run it. I clicked ok and then it did something and left me with a "firefox" drive on my desktop and a firefox.dmg file. I am supposed to be doing anything with those? Can I delete them? Thanks and sorry for the stupid easy question.

 

oh... i got it now. that's easy.

okay just one more question for now:
for example my gmail account (i have tons of invites if anyone wants one) went you go to the sign in screen there is a option to select to remember your user name and password for two weeks. on my pc i was able to tab down to that. however when i tab with the mac it brings it back up to the address bar. anyway to tab or do a keyboard shortcut to get to the same effect? thanks.

 

i think the greatest part of my mac experience is this:

so a few months ago i started looking into getting an apple laptop after my compaq pos died. so i told my parents and i don't think they took me seriously. as i am getting closer to buying they are saying things like "are you sure it will connect to our network, blah, blah, blah" and i told them it would be fine. they were like "i really don't think it is a good idea, i think you are going to have lots of problems with it." so i get my ibook and turn it on and it picks up on the wireless signal immediately, i put in the password and i am on the internet in less then a minute and then tell my parents "is there anything you want to check on the internet!" they just had a disgusted look on their faces. awesome.