OK, you sound like a down to earth fella and salary for your experience and field sounds abt right.
Suggest you sort out the school as some have said and then you will see.
Don't be stuck on the idea that you have to be on the island tho (even if you work on the island) - sometimes (not always) it can be a good thing to live on Kowloon or NT. Not all HK island accomodation cost 30K but it is definitely more expensive than most places on Kowloon and NT (not all tho).
But first yes, take a look at the schools.