A Floating Form Button is a good alternative to the Add button when using a details style layout. Filtering is a little more complicated, because you have to build your own filtering functionality which may be a choice component, user specific column to hold the choice, and a couple more columns to make the filter work.
Can you explain more about tweaking the look of the list? Are you trying to apply CSS? If so, then yes, you are stuck with the details style layout.