There are no serious problems with diseases in the Maldives. Beware that tap water may not be drinkable at all resorts: enquire locally. The Maldives are malaria-free, but some islands do have mosquitoes and catching dengue fever from them is possible, albeit highly unlikely. For those coming from regions infected by yellow fever, an international certificate of inoculation is required.
Most of the problems come from diving or sun related injuries. Heat stroke always cause problems in the tropics but couple that with divers spending hours at a time on a boat wearing a wetsuit and overheating of one form or another is a real issue. Keeping this in mind, such injuries will be easily avoidable as long as you drink lots of water and get into the shade as much as possible.
Lots of the resorts have their own doctor or nurse and most are within easy reach of the decompression chambers. Male has an efficient and fairly modern hospital but bear in mind that it is a long way to get medevaced home from.
Maldivian Dhivehi, a close relative of Sinhala spoken in Sri Lanka but with borrowings from Urdu, Hindi, Arabic and many other languages, is the official language. It is written in a remarkable hybrid script called Thaana, which uses Arabic and Indic numbers as the base of the alphabet, written from right to left with Arabic vowel signs. The script is thought to have originated as a secret code for writing magical formulas so that outsiders can't read them, which would also explain why the ordering of the alphabet is, as far as linguists can tell, completely random!
English is widely spoken, particularly by government officials and those working in the tourism industry. English is the language of instruction in schools, which means that you will be able to communicate with the locals with varying degrees of difficulty.
Since Maldives happen to be a popular destination for German and Italian holiday goers, a sizeable number of local resort workers are able to speak fluent German and Italian. This may vary depending on the resorts you plan to visit, though.