Questions about masking fluid

[Lady Hope]

Hi everyone,

I am hoping that someone can help me with some questions about masking fluid. I usually do paper crafts or sculptures but I have been venturing out into painting and drawing lately... mostly so I will be able to draw my sculptures in advance and have new techniques for painting them.
I just discovered masking fluid and have used it successfully with watercolours, but I want to try using it with acrylic paints because I have a great idea and prefer acrylics, anyway. (Also, I have no more watercolours and can't spare the money right now, so that doesn't help!! )

So I have 3 questions:
Can it be painted on top of acrylic paint that has already dried? I have an old canvas with a background already painted...I would like use it, if possible, instead of using a blank one. It is really nice and I have no other use for it right now. (It is the inspiration for my great idea!)
Does anyone have a good website or resource about using masking fluid with acrylic paints?
Can it be used with watercolour pencils?

Thanks in advance for your help!!