1)The weather will almost certainly be very hot. (30+ degrees, maybe nearer to 40)
2) I haven't been for a few years but don't remember mozzies being a problem.
3) Alcudia has loads of restaurants of all kinds, you'll be spoilt for choice. A meal for a family of 5 could cost anything from 20 euros to 100+ depending on where you go.
4) As with any holiday, trips will be a whole lot cheaper if you book them locally, not through your travel company rep.

i think there is a company called no frills excursions. who offer excellent value for money from the alcudia area.

http://www.nofrills-excursions.com/principal/index.php

As swanseajack has said, these offer good deals and I will be using them again this year.