I was thinking about the fact that a WCV, for example, can start his/her power just by looking at you. A medusa, on the other hand, is limited to you looking at her (or into her eyes). Which you can avoid by not looking at her, using a mirror, a phone, VR goggles, whatever. For that reason I use the additional -1 Improved Gaze option for elder medusae or other petrifiying kinds of monsters, which would put it back to -4 again. It's not according to RAW, it's more like according to what I feel it should be.
As for the grapple - yeah, I agree. First the medusa tries to establish a Locked Eyes (or Peering into the Abyss or whatever suitable name) aspect with her Petrifying Gaze. If successful she can, on the subsequent exchange, tag that aspect and start a grapple with her Locked Eyes (= Incite Restrictive Effect) power.