No problem buddy.
1) Yes its usual practise.
2) No laws really, depends on the landlord. Some will ask for two payments or three if you are lucky. I have heard of noone doing this on a monthly basis as in the west. Thats not to say its impossible, just unheard for me at least
3) You can get a bank loan if you have residency and a decent job (14K is decent) but then again depends on how much you want.
4) In terms of medical coverage, some companies do not offer it. You can always buy a medical card (I think its mandatory but I could be wrong). If I am not mistaken its 300AED/annum. It gives you considerably reduced prices for medical coverage (used to be free for expats before). Dental is not covered I think, but I will be moving there by the fall I hope and my wife is a dentist. She will offer special pricing for Dubai Forums members at that point. I will advertise when the time comes.
You are very welcome. Do not hesitate to ask should you have any further questions on this or any other matter.