but fixed wing air to ground fighters - also with air to air capacity - could be a big win in those missions
May be, but certaintly not fixed wing EW&C. That belong to aircraft carrier.
In China's case, realistic expectation of amphibious assault engagement would be either in Taiwan or South China Seas. In either scanario, KJ-600 from type 003 (and may be type 004), and shore base KJ-200 and KJ-2000, and future Y-20 based EW&C would be part of the joint operation that will involve in space, air, land, cyber-space and sea engagement.
I don't expect KJ-600 to be able to operate from type 076 due to the width and length of top deck, limited hangar space allocation and engineering support.
I do not foresee type 076 to act alone with-out aircraft carrier and escorts. There won't be American style of global policing for China in the next few decades. And we cannot use the examples of US Navy and US Marine's LHA/LHP and F-35B to visualise future PLAN type 076 operations.
LHP or LHA should be doing what it do best in beachhead assault instead of trying to be a jeep aircraft carrier. Fighter jets, Strike jets and bombers can be supported by Y-20UA, while type 76 would carry UCAV to supports marines on the beach with their air to ground strikes as well as pin pointing enemy locations for guns/rockets and missiles..