x2 on the wire wheel, preferably on an angle grinder, you want to get the metal as clean as possible. It's hard to say for sure, but particularly on the second photo, there appear to be a few areas that may be rusted all the way through, meaning rust converter as Dirk notes will not be a fix for that - there will be small holes in your floor. So, best remedy for that is either a whole new floor welded in (lot of work) or patches made and welded in (also a lot of work but less). Then after the rust converter has done its job, good quality primer and (preferably 2K, can be in rattle can) paint.