Hi Papa Tang - you are going through a very exciting chapter of your life ! These are cherished moments indeed: take it from me, a papa who has gone through it 3 times. ( I'm not talking about the bugs). In the twilight of my years I treasure these moments s I' sure you will when you reach my age.
As for the yellow beetles I've yet to find one that can control this pest. 'Search and destroy' is the only way. As for the mealy bugs the method you intend to use is as good as any - use the water-based aerosol spray - but I find some flower buds may abort from the spray.