Jenny, I'm sorry, but I don't know how I missed this topic for so long!
I just let my own nails grow and polish them, but my answers are (same rules apply for toenail polish):
1. No clue.
2. I wait AT LEAST one hour before I use my hands for anything. I try to wait to apply the second coat several hours later, if not the next day.
3. Experience tells me that after one hour, I'm pretty safe. The longer you wait, the better, but after two hours, they won't really get any drier. Even after an hour, if you press down on the polish, it doesn't take much pressure leave a fingerprint impression, so I try to have a movie or two ready to watch when I'm doing my nails (which I'll be doing tonight). Also, being on-line helps the time pass, too. NEVER do your nails right before bed, because even if you think they're dry, you'll probably smudge them in your sleep. I have long hair, and sometimes I ignore my own rule and wake up with fine scratches in the polish where my hair made imprints. If you just painted your nails for one day/night, it doesn't matter, but if you plan to wear the polish for a while, take the time to do it right.
4. No, not really (not enough to matter). If you're in a big hurry, the best thing to do is fill a sink full of cold water and plunge your hands (at least your nails) into the water for a couple of minutes.
5. Cold temperatures are better for drying nail polish. Heat just keeps the polish all sticky. In addition to the sink method, you could also try sticking your hands in the refrigerator or freezer for a few seconds, but that's not very practical.
General Info:
I use two coats of color (on rare occasions, I'll use three, depending on the color), followed by two clear coats. I try to wait two or three hours (if not the next day) before applying the second coat of color, unless I'm in a big hurry, but then I have to be even more careful. I don't ever put the two clear coats on during the same day. If I still have the polish on a week later, I'll add another clear coat to keep it going. Sometimes, especially with toenail polish, you can keep the color looking good for two to four weeks, depending on how fast the cuticles grow out. With fingernail polish, a week or two is really all you can expect (two is very long), because we use our hands so much.
Never apply really thick coats. Use a thin coat to start, even if it looks a little translucent. The second coat will make up for any weakness in the depth of the color, so don't worry. Thin coats dry faster and smudge much less easily. Thick, gloppy coats take forever to dry, and are prone to showing marks/impressions.
Conventional wisdom recommends that you start with a brush stroke in the center of the nail at the base of the cuticle, and paint outward toward the tip of the nail, then repeat the strokes to the left and right sides. I do that, but just before, I'll run the side of the brush along the tip of the nail, to make sure I get the edge covered with polish. Then, the normal strokes smooth it out. I do the same thing with the clear coat, because that helps protect against chips at the tip of the nail (the most common problem area).
Try to plan ahead and do you nails when you know you aren't going anywhere on a given day. That way, you don't have to worry about painting inside the lines, and it's easier to get complete coverage. Later, when you shower/bathe/wash you hands, you can easily rub off the excess polish that got on your skin. If you paint your toenails one evening (not too close to bedtime), then wear socks and shoes all day the next day (especially thick socks), most, if not all, of the excess polish will be rubbed off. Then, wash off your feet, add the first clear coat, and you're looking great.
Of course, if you need a manicure or pedicure right away, you have to be perfect with applying the polish, but if you plan ahead, you'll get better results, and it will be much easier. Once you've got the polish on, act like it. Don't grab things with the tips of your fingers, don't push buttons with the ends of your fingers, don't use your nails to rub the shampoo into your hair (that damages your polish more than anything else), etc. Baby your nails as though your getting paid to keep the polish chipping.
Oh, another tip I almost forgot is to keep you nails moist. The best time to polish your nails is soon after taking a bath or shower, because your nails are nice and moist, and the polish will lock in some of that moisture. The drier your nails are, the more brittle they are. Ideally, your nails should be soft and flexible, so that if you hit them against something, they'll tend to bend a little instead of breaking, as do dry, hard nails. Also, when you aren't wearing polish, use a moisturizer on you nails (any lotion will do), especially when you go to bed.