Your lungs may or may not ever recover to 100%, so that's a bit unreasonable to answer. However, the timeline for recovery is quick for some things, long for others.
Within about 72 hours, pretty much all the nicotine and nicotine metabolites will be cleared from your body. Within about 2 weeks, most of your gum circulation has restored itself, and any addiction cravings you have are psychological, not physical.
Anywhere from 1 month to a year, most of the cilia (small fingerlike projections in your lungs that help move phlegm and other fluids) will have recovered and/or reestablished themselves.
After that, most of the improvements are in the risk factors, extending out up to 20 years after quitting. This includes the risk of smoking related tooth loss, heart attack, strokes, etc. You will always have a slightly higher risk than a non smoker, but way less than someone that continues to smoke.
As far as aiding the process, simply stopping is the biggest thing. Watch your food intake, as smoking raises your metabolic rate, so when you quit, it will drop down and may fluctuate a bit before it stabilizes. Avoid the temptation to replace cigarettes with food, which is also common.
Good luck with the quitting, and welcome to a healthier lifestyle!
