Visiting Malta for 3 days

Hi all,
I will be visiting Malta for 3 days mid December. I have few questions which I would love to have your point of view on:
- What would you advise me to see within 3 days?
- Is it easy to use public transport in Malta- from the airport to Valletta, vice versa and in town?
-Would you rather go for car rental? Is it easy to find parkings and drive in the city etc..?
- where would you recommend to eat to try the traditional food of Malta?
- Are there local markets during week ends and if so which would you advise?
- How is the weather like currently there? should I dress warm or light?
In any case, I would love to meet you guys whilst I am there (locals and expats) and I look forward to attending internations events as well whilst I am in town!
xxx
roubina