Debian :: How To Download Stable Version And Check MD5

I want to install Debian Stable 8 Jessie. I've tried the main website, of course, first. But there are a lot of options there to download Debian 8: CD, DVD, Live etc. I downloaded debian-live-8.0.0-amd64-lxde-desktop.iso and I booted live in VirtualBox. It boots fine and the operating system looks in order.

Questions/problems:

1. The desktop icon for the installer says "Install Debian sid". But from what I know "sid" is unstable version. I do not want unstable, nor testing. I just want normal Stable. Did I got the wrong version? The website is a bit confusing about which version is which.

2. How do I check the md5 of the iso? I know how to do that with other distros, they usually specify it near the download link and I can execute in terminal the command 'md5sum' followed by the specific linux distro iso and then compare the numbers. But I can find no such thing for Debian. I searched the website but could not find any clear info.

3. After I install, what should I do in order to make Iceweasel work with Flash and multimedia codecs? I also need Skype and the proprietary Nvidia drivers.

And if I enable these non free, do I get automatic updates for them like for the rest of standard Debian software? Or, if not, what should I do?

The idea is that I want a system that is as stable and bug free as possible, but I won't use many apps beyond these ones. I don't need the latest and greatest software as long as these get security updates. Should I be ok with this configuration?