In answer to your first question:
Contrary to popular belief, windowsills are not the best place for ripening up tomatoes. Take a close look at your tomato plants and you will learn why: surprisingly, tomatoes often start to ripen on the opposite side of the fruit to the sunny side although not all varieties show this. So, plenty of light is not required for ripening and, in fact, it tends to make the skins of the fruits harder.
Temperature, on the other hand, is a very important factor. The warmer a tomato fruit is the quicker it will ripen. So you can slow down ripening by placing tomatoes in a cool area or speed them up with moderate warmth.
The third factor that speeds up ripening is a gas called ethylene. This is the gas that is used commercially with tomatoes and other fruits that are picked green before shipping and then ripened for sale. Although this all sounds very artificial and leads to rather bland-tasting produce, ethylene is actually naturally released by ripening fruits such as bananas, apples and tomatoes. So, placing a ripe banana or apple in with some green tomatoes in an enclosed space helps to speed up the ripening process.''