New Tank and 2 Mollies

Question
Hi Alex,

I have just bought my first fish today. The pet shop recommended 2 mollies. I can't tell whether they are male or female!  Its a second hand tank that I am cycling with the mollies but I think there may be a problem.  I treated the tap water and left it for 4 days before getting the fish and have put some biological aquarium supplement in today before the fish.  
They were fine for a few hours but haven't moved from the top of the tank for a few  hours now.  I have an under gravel pump with two of the tower things with airstones in them.  Will they be ok?!  I am trying to get the temperature right too as my new thermometer says its around 24-25 but they are staying at the top near the heater.

Also, I wasn't really sure I wanted livebearers as I am just getting used to fish keeping with a small 10 UK Gallon tank so i am not sure what I will do with any babies?

And one last thing while I'm at it!, what would you recommend as my next fish ince I have sorted these out and  how many would I have eventually.

Sorry for the millions of questions in one

Kind regards, Chloe

Answer
Ok i would put the heater to 77 degrees farenheit and put an external filter on the back of your tank. Also i am not sure how big a 10 gallon UK tank is in U.S. gallons so if you could tell me that i could give you an answer on your next fish. They are just scared from moving from one tank to another and they are also just getting used to their new surroundings. To keep a healthy and stablized aquarium you should do weekley water changes and put stress-zyme in the tank weekley. To tell male from female is when they are babies for most fish, but i really can't tell otherwise sorry.