Hiya clairey,
For the weather, go to the top of the Turkey forum and look for daily weather reports from turkey, a few of the members live in or near to Marmaris.
As for your Apartments, they are in Armutalan, they are roughly 20-30 mins walk down to the beach. Or you can get the Dolmus (little bus) down to the beach too, they run often so you wont hav a problem catching one.
Here is a thread about the aparts
http://www.holidaytruths.co.uk/viewtopic.php?t=32364&highlight=antique+palace
To see roughly where you are staying
http://www.bekcibasi.com/eng/antique/hotel.htm
click on location, at the bottom right click city plan
it will show you Antique Palace hotel, it is close to yours.
Loulou