Fast (high) frequency hopping with off-the-shelf components
I would concentrate on the VCO and try to find a design that has a reliable change in frequency per volt. Something that can almost be run "open-loop".

This is a priority because my suggestion would be to use a PLL but with feedforward to get you the speed (and distance to the next hop) then the PLL loop would tweak the final few MHz. So how accurate and in what time do you want it to be?

You can get quadrature outputs using two resistors, an inductor and a capacitor across a vast range of frequencies but with some amplitude variations.