IE is currently the standard. If you don't understand that, I am certain you are not really a web developer.
No, IE is the majority browser. It is not the standard.
When I develop for public business I use a subset of CSS that IE can understand, kind of like tying my wings. When I develop intranet I develop to the target browser, currently IE for this job.
When I develop personally, I use the full features of CSS, screw anyone stupid enough to use such an outdated, incompatible browser. Maybe seeing my site will encourage them to get a decent browser (which I recommend).