Based on those pictures, buds are ALREADY forming on your plant. The clusters with the white hairs sticking out are the plants flowers. Right now, they are just "baby" flowers. When the clusters of flowers grow large enough, and you dry them, they'll look like the herb you're accustomed to seeing in the bag.
Impossible to say EXACTLY, but typically plants take 7-8 weeks after flowering starts before they're "ripe" for harvest.
The way to know exactly is to examine the plants resin glands ("crystals") carefully with a strong magnifying glass or microscope. As the plant matures the glands will turn from clear/colorless to white to amber/yellow. When about 10-15% of the glands are yellow, the plant is ready to be chopped.
Not really. It depends on the exact strain, but these plants still typically take 7 weeks or so after flowers start forming before they're ready for harvest.
Unless the plant is entirely tipping over (and even not necessarily then) you probably don't need to do anything. The plant will straighten itself out naturally, or just grow upwards.
Sometimes plants get really heavy with buds and can sag or bend over under the weight. If you're lucky enough for this to be a "problem", you can reinforce the plant by tying it to a stick stuck in the pot like a tomato stake.