1.
"Can two controllers work one frequency to increase capacity"
possibly, yes.
Why would a unit want to though? Pay for an extra controller to deal with traffic that (if they aren't a LARS unit), they aren't getting any £ for?
My previous unit used to open up 'Radar 2' on occasion to deal with busy periods, sometimes split one ATCO working IFR inbounds and outbounds, the other 'dealing with' VFR (i.e. talking to them, and generally keeping them out of the way of the approach - co-ordinating transits when possible, but more often than not giving them routings through CAS that kept them away from the IFR stuff)
2.
“How many simultaneous VFR transiting aircraft should it possible for ATC to handle?” (qualified with "VFR transits which would involve little work")
X amount! If the transits involved 'little work' (for example crossing a portion of CAS not in the approach or climb out lane, at an altitude not getting 'in the way' of IFR) then quite a considerable number can be handled. All VFR, the ATCO only has to provide traffic info by means of 'separation'.
As someone mentioned above, once you get IFR traffic in the mix, can get more complicated.
Back to the length of your piece of string!
Last edited by dan saaf; 22nd Jul 2013 at 09:01.