1. Whichever is cheapest.
2. Depends how thick you want it. Use less acetone and add more if you want it thinner.
3. Don't know. I left mine overnight.
4. Depends how much you use. It dries pretty quick, but I would wait at least a few hours.
5. It lasts forever. If it gets to thick or hardens, just add more acetone.
Those were my experiences.
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