Oh little GuppyLuver, you tank is VERY small. (I say little b/c there is also the new GuppyLover92 and your number is smaller :)
Why not just get 2 males. That size tank leaves no room for fry as well and the males are pretty and won't fight.
I'm not sure on how to cycle a tank that small without already having access to some gravel or filter medium from another healthy tank. I would guess you would just have to add the fish and make sure you do frequent water changes. Water changes I think should be about 20-25% twice a week and water should be seasoned ie. have the chlorine reomoved.
Leaving a tank empty, before adding fish, does nothing unless you add ammonia to it to start the "good" bacteria cycle.
I would suggest that you try to hold off until someone more cluey than me comes along and can answer your questions. I'm not sure about your heater either. Turn it on and test it out to see what temperature you can keep the water at.
Good Luck
miskairal
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