Hmmm, I am not sure my opinion is completely inline with others, but I will give it:
I use a single line attached to the pull (bow) of the boat. I do not like dual lines as it is just one more thing to mess with when trying to get her up to the boat (for any reason). I use an inflateable too. I personally do not use a floating painter becaues I have never liked the line and seems apt to chafe. But many dissagree with me and if you wrap it around your prop it is all for naught anyways. On the painter I put a snubber:
This keeps the shock off the line and makes the tender ride a LOT smoother. I highly reccomend this. I also put a loop in the painter at the point where I can pull the dink up to the back of the sailboat. THis make for easy connection when trying to pull her in for any purpose (especially when moving and you have to connect her quickly).
I have not found a sweet spot when towing the dink. SHe always seems to slide down the wave faces and 'Pop" anyways. The snubber helps, but there (to me) does not seem to be a perfect place. I don't bother trying to adjust that. If I get caught in a storm, I will often try and pull the tender in close (ie, the loop). THis works pretty well unless the seas start breaking behind you. Make sure you have the plug out on the inflateable. Many dissagree with this, but your inflateable should not fill with water if nothing is in it. But the plug will help you get the water out as the rain or seas break into her. Otherwise, you will find you ahve a major situation on your hands when she starts to fill up!! (Don't ask me how I know).
DOn't. If you can deflate her, do it and toss on the foredeck (securely lashed down). Do not leave her on davits either unless you are certain of your weather. I personally feel a towed dink is dangerous offshore - assuming it stays with you the whole trip anyways. Towing her in seas is tough on the hardware and peace of mind.