Bands / overbite. The elastics are not likely the most important part in the resolution of your overlapping overbite. Opening a complete overbite is quite variable in difficulty, requirements for things added to braces, and time. Ask you orthodontic specialist for a time estimate and what will be required to fix the issue.
Varies. Time to correct an overbite varies according to the severity of the problem, patient cooperation, and growth. It also depends on what else is being corrected simultaneously with the overbite correction. Ask an orthodontist to examine you and give you a time estimate.
Braces. I'm not sure i understand your question. An overbite is not corrected by rubber bands. A 100% overbite means you have a deep bite. An overjet means your top teeth stick out too far compared to the bottoms. Rubber bands can correct an overjet. How long it takes depends on the amount of overjet in millimeters.
Depends. Ortho corrections are based on a wide variety of issues...It can take a few months to a a couple of years. After having an orthodontic evaluation, the doc will give you a time frame. Additionally, often orthois slightly overcorrected so that the mouth stabilizes at the desired position...Need to discuss with doc.