I can answer 1.5 of those.

Yes, it is easy and fast to get to Miami Beach from the airport by car.

Ask your hotel about parking. I have only parked on the street, which is cheap and available and takes credit cards but is not suitable for overnight.

Have you googled parking garages deco district or collins ave or whatever?

In my experience the best thing to do is to take a taxi from the airport to Miami Beach. The rate if fixed - something around $30. You don't need a car in MB area proper, so no need to rent one at least for the first part of your stay.

If you want to rent a car while there for day trips check out Thrifty - they are at 1520 Collins in small storefront. You save a bundle over renting at the airport, and save on parking as well.

You should be able to drop off at the airport for no fee.

Thanks for the replies. I think I am will get the taxi from the airport and then hire car from Thrifty for excursions. When I initially checked, Thrify at 1520 never came up, this is so easy for us to get to and dropping off at airport is ideal.

You don't need to take a taxi from the airport to and from Miami Beach unless you really feel the need. There's a very reliable bus, the Airport Flyer (#150) that goes directly from the airport to Miami Beach -- in my experience, quick and direct. It has one stop at the Earlington Heights Metrorail station, then once it reaches Miami Beach it runs from 41st Street south to the Lincoln Mall in South Beach. It's available seven days a week from ca. 6 am to ca 11 pm.

Thanks for letting me know that. I was nervous about the Flyer as I thought it would be slow.
Another question - I need to get a car to go to the everglades but the problem is the car hire place closes at 6.00pm - does anyone have suggestions of a good reasonable priced place to leave the car over night (nr 1500 Collins). The hotel charges $32 is that good - bad - or ugly??

$32 would be cheap in Boston. Can't say for MB.

Here's the link to the Flyer bus:

http://www.miamidade.gov/transit/library/airport_flyer_brochure.pdf

If you want to try getting to the Miami Seaquarium using public transportation, it looks like it can be done.

You'll need to take the "C," "S," or "120 Beach Max" bus to the Government Center Metrorail stop (the Beach Max is a limited stop bus and thus a bit faster). Get on Metrorail and go to the Brickell Metrorail stop. From there, take the "B" (also called the #102) bus to the Seaquarium.

http://web.miamibeachfl.gov/parking/scroll.aspx?id=30958

Here's a list of garages. Lot G4 is 16th and Collins. It's a garage. They are usually $1 an hour - Its probably a max on $20 for the day. If you are multiple people sharing a cab is usually cheaper. And someone said it is a flat rate from the airport.

Thanks to all of you who have replied, your answers have been really helpful. Plans are finally coming along nicely.