1) If you're talking from germinating to ready to smoke (taking into account the curing process) average time is about 4-6 months, all depends on the strain and how big you want your plants.
2) Depends on the temperature of your room. Normally 2 - 3 times a week depending on how dry the top layer of soil is, some people can even tell by their plants weight (from wet to dry) to know when to water. Better to underwater than to drown your plants though.
3) I'm from the UK and I've heard positive reports about Bio-Bizz soil and nutes, but if you're in the States I'm not sure what to recommend.
4) As before, depends how big you want them. Some people like to grow to 12 inches of veg growth (18/6 or permanent 24 light) before switching to flowering (12 hours of light, 12 darkness). It takes a few months anyway...
5) If you've harvested before your plant has had the chance to fully release it's THC potential then no. Looking at the trichomes (the small white crystals) indicates when your plant is ready. Some people chop when they are amber, others go for milky white depending on the type of high/stone they want.
6) You want to be smoking the buds. If you look at a cannabis plant and strip it of it's leaves, the hairy pistol clusters at node regions - those are your buds. However, save your trim (leaves, etc) because you can make hash/hash oil/butter from these.

Invest in a good grow book dude, because as the previous guy pointed out if you don't know what part of the plant to smoke you're nowhere near ready to grow yet. I haven't even grown any cannabis myself yet but I was able to tell you the above info just from reading some literature. (Experience growers if I've misinformed anything in my post please feel free to correct me..)