Some kites need a tail for stability because a tail creates drag that points the kite in the right direction. Other kites only have tails for aesthetic purposes and are limited only to your imagination. Keep in mind though, that a tail that is too long can create too much drag and make it hard for the kite to fly or take off.
For the most part, Delta kites don’t need tails. However, if you are flying a kite in turbulent weather you will probably want to add a tail for stability
There are a number of kites that fit the bill. One particularly solid kite that is easy to fly and interesting looking is a box kite and all of its variations, including the winged box site. Other eye-catching kites would be hexagonal kites, and star box kites. Those are all single line kites. For dual line kites, you can pick from a wide variety of standard Delta kites with interesting designs.
Kite tails are quite simple to attach. First tails should be added symmetrically, so it is balanced on both sides of the kite. Attaching the tails with tape is the simplest method.
About 5-25mph is the best windspeed to fly a kite in. Anything less or more than that makes it either too hard to get liftoff, or too hard to stabilize.
The answer depends on the type of kite being flown, the windspeed, and the height of the kite. However, if the wind speed drops too low, and you are not working the kite, the kite will fall regardless. So, tying to something for an extended period isn’t really an option.
Simply put, kites fly because wind pushes on them. The wind exerts and upward force on the kite, keeping it aloft.