Ok. The current login/register form that I'm using, do I place it in the Login and Register positions as well? If so, would I be able to delete it from the right side panel, where I currently have it on the site?
Yes. If you place the Login/Register forms in the Login/Register positions and assign text to those positions in the theme options, then the buttons will show the forms and you won't need the sidebar widget.
Right now, the entire post shows on the homepage(s) ... I would like to have the summary/excerpts so the 'read more' can serve its purpose. Sorry, that's what I meant by the 'read more' doesn't work.
Do you have the site set to show a summary on pages with multiple posts (Settings -> Reading)? All the code is there to make it use the post excerpt, if one exists, but if it's not working correctly, there are plugins that will auto-generate an excerpt for you so you don't have to type one in.
Ok. Just to see if I understand, right now, I have to go back individually to each posts and change that option manually? There's no way to do that automatically for all posts?
Unfortunately, no, there's no automatic way to change all posts, but I definitely want to add a global override for it in the next major patch, I just have to wait for some admin changes that are currently being worked on by another developer.