Hi Toyturner,
Without the details of what programs you installed or information from the logs its hard to say exactly what caused the failures. However I have seen that in cases where someone tries to install multiple applications at once the same dependency failure ( ie: failed SQL login) can cause then all to fail. Techincally there is no need to install the applications separately but from a troubleshooting and isolation perspective then yes this might make sense in some cases.
Regarding the Amplifeeder question there are two dialogs. The 1st page has an option to enter the "Application Name" , which you can change to whatever you want. The 2nd page is where you enter the database information. What you enter here depends on whether you choose "Use Existing Database" or "Create New Database" . I'll take a guess here if this is the 1st installation you choose "Create New Database" . The next option is for the Database Administrator and Password. This defaults to "sa" for the Database Administrator and depends on your SQL installation and what you set up for an Administration acccount. If you are unsure of this you will have to check this with SQL Admin tools. Next is the Database Username . For a new database this is whatever you want to set this to . The same will apply to the Database name.
I hope this helps some. To isolate this further the installation logs are located in one of the following locations depending on your operating system.
Installation Logs:
Vista / 2008 :
%localappdata%\Microsoft\Web Platform Installer\logs
XP, W2K3:
%USERPROFILE%\Local Settings\Application Data\Microsoft\Web Platform Installer\logs