1. Tags and Categories are displayed on your blog to assist readers to locate related content in your blog. The iNove or Monochrome theme do give you the option to hide categories or tags on posts (under theme options). But for other themes purchasing an annually renewable custom design upgrade and using CSS editing to hide tags and categories is required.
Important note: CSS editing is theme dependent. In some themes, categories and/or tags cannot be hidden independently, as they are in the same selector as the other meta data elements such as author, date, and perhaps even the “leave a comment” link, which means if you hide one, then you hide them all.
2. Click the title of any post and you will see the sharing buttons on the bottom of the posts when displayed on their own page. If you want them to appear on the front gaoe the see here:
I can’t see the buttons on the front page.
Make sure to select “Front Page, Archive Pages, and Search Results” for “Show buttons on” setting. http://en.support.wordpress.com/sharing/#troubleshooting
In a new blog one does not have many posts or comments. In an established blog if the comments did not collapse on the front page it would become a mile long in no time flat and page loading time is a page ranking factor. We have only seconds before visitors refuse to wait and click out. Unless you use P2, a twitter-like theme comments are collapsed on the front page of your blog and posts are showcased there. The way the comments function is coded into the core of WordPress and you cannot change that.
3. The Settings > Reading page "summary" setting is only for your RSS Feed for posts. To display only excerpts of posts on the front page of the blog you can split content by editing the posts and inserting "the more tag".