Hi,
Well june is not the best time to visist the Maldives - chances are you will lose the odd day or two to rain but beleive me, even the Maldives when it's raining is better than anywhere else in the world. I've been 3 times- the last of which was in May and although we did have a bit of rain, it certainly wasn't enough to ruin our holiday - in fact we have just yesterday booked to go back in May 2007 so you can tell we enjoyed it then.
Re the seaplane transfers - it really depends what island you are going to. Some of the islands come with seaplane transfers included as getting a speedboad transfer is not an option as it would be far too long a journey - what island are you staying at? If I did go by seaplane though I would investigate asking the hotel to arrange it for you after you get a price from your UK travel agent - transfers are usually around $275 if booked in the Maldives for a return trip which may be cheaper then you can get in the UK - it must be booked through your hotel though, the seaplane company does not take bookings direct.
The seaplane transfer is part of the Maldives experience in my opinion - fantastic way of seeing the islands - plus if your transfer is over 2 hours by boat you might not feel up to it after an 11 hour flight from the UK.
As for the water bungalows, that it us too you. They are very expensive so if you are worried about your budget expanding rapidly why don't you wait till you get there and ask if you can upgrade for the last couple of days of your holiday - that way it should be no more then a few hundred dollars extra.
As for diving and excursions- do not book these in advance, book them with your resort and island dive school when you arrive - much cheaper.
There are sharks in the maldives - I was snorkelling in May and came accross 3 white tipped reef sharks but they won't come too near you are are way more scared of you then you are of them so don't be too freeked out about them.
Any other questions just ask.
) is worried about diving - are there sharks?!? 
