1 - The mentioned and tagged options in your screenshot look to come from a modification, more than likely a DB Tech mod - I would check the plugins from said mod(s) to see if you can easily disable it from displaying in postbit.
2 - Ahh so you want a clickable link or button that when they click the @Usersname it does some sort of function such as send a PM or open a chat dialogue? That is not standard by default if so and will require a modification (honestly I believe DB Tech has one available for that too). If you meant something else i.e. simpler addition this article may help -
http://www.vbulletin.com/forum/forum...tbit-templates
3 - That could be easily done by simply adding this to the additional.css template:
Code:
.userinfo {font-weight:bold !important;}