Post installation

I am very new to Drupal and am developing a site to manage teams participating in a contest, when someone signs up, rather than calling them a 'user', I would like them to be a 'team' - so they would see 'Team Name' instead of 'User Name'. Is this possible?

Alright, I changed my forum to a new theme and thought I was done so closed my window and closed the machine, now on startup, I realize the theme I chose has no access to login or admin area. How do I force drupal to change the theme it's using?

I'm attempting to use this theme function:

I'm in the process of re-designing one of my sites so that it uses Drupal rather than hand-coded pages. The site consists of a fairly large photo gallery (currently using Gallery 1 but plan to migrate to G2), various pages about things we get up to/thoughts/so forth (will most likely use the blog feature for a lot of this) and also information about therapies my wife does. So all in all nothing to technical and Drupal will easily cope with it all.

I've been trying to figure out medium vote for a couple of weeks. It only displays the voting widget for some of the nodes. eg: some blog posts have it but some don't. Is there a setting I'm missing? The same occurs with images,stories, and pages. The problem has persisted from 4.7.2 - 4.7.3. Anyone else out there ran into this same problem?

I'd like to simply have a note, or comments box that's processed with each checkout of the shopping cart. Is this available through the default ecommerce module?