Following the advice of both a knowledgable friend / Sprint sales person, and the users on the forums, the first thing I did after opening the phones was to invoke updates of the Operating System and email application. I knew from following the forums before buying that a major, long awaited upgrade had occured in late November and and the email application had been updated in early December. The update allowed the phone to use some Java applications that needed a keyboard, and view Office and PDF documents when attached to an email.
And again, following the advice of the forums, I installed my first application. Opera Mini. The built in browser is okay, and apparently a lot better than it used to be, but Opera Mini has a better reputation. I downloaded from here.
One nice thing, you can download the PC version of Opera and synchronize bookmarks between your desktop and mobile. I don't want all my desktop bookmarks on my phone, but having my phone's bookmarks on my desktop makes it easier to edit them and add new ones.