For your studio work, you have to find out what FL is good. For my basement studio I determined that my perfect FL is 65mm (I stand as far as possible, to maximize the usage of the paper background, and still can cover the whole width of the background in portrait mode). I used 55-250 for a while, wasn't happy with the quality, just upgraded to 70-200 f4L, it should be much better match.
Regarding 85mm too tight indoors - I don't think so. I even manage to get some nice shots with 135L on crop indoors; 85mm would be easier. It is not perfect for indoors, but given that you'll be using it outdoors as well, 85 f1.8 sounds like a nice compromise. I heard this lens has fast and accurate AF, great IQ.