Currently it is not possible to specify the mobile project you want to launch by altering the URL, but this is a good feature request.
As far as the mobile screen sizing, to really get rid of pan/zoom what you probably want to do is to get your screen roughly the right size and then choose the “Fit to Device” option. That will make the mobile client use the actual mobile device’s reported screen size as the project size, which should give you a perfect fit. (I say “should” because some mobile OSes are better than others at this. Early iOS devices were not very good, but newer ones work well)
