Make sure you get you new tank running first with 1/4 to 1/2 of the water your old tank. once that is done let it run for at least a couple of hours with the new pump. But as for the fish they should be fine for a day or two without a pump but the need a heater. You might start to get foggy...
If you get a divider do NOT get a transparent one they will try to attack each other and hurt themselves. Get a filter appropriate for a 10 gallon tank but not a heater. finally i would recommend getting NATURAL not coloured gravel because the coloured ones can cause problems in the future...
Like guppies platies come in a variety of colours and patterns and you never know what to expect but it sounds like you got lucky with this one. also I had gorgeous colours on my babies to have then latter fade away with development.