1st u need to use the correct AF mode. hit the 'i' / 'zoom in' button, n scroll down to the 2d lowest icon on the right. hit OK and select either the middle (better for moving subjects) or bottom one (bttr for static objects for some reason ).

now u can change the AF area by pressing right or left. u can see the red lights change as u press
how cheap is cheap? google quite hard to find...i just look at yamiya.com.my. go to lenses n accessories > lenses > nikon or other brands. knock urself out

nikkor is just branding my fren...got cheap nikkor rm400 only, also got expensive nikkor up to rm30,000, even more i think. look for sigma, tamron or tokina brands too...they make lenses which are cheaper than the nikkor equivalent (in terms of range n speed), but most of the time the quality, build n performance is lower

oh one more thing... since u're using D3000... u can only use lenses that has autofocus motor. which are more expensive than the equivalent lens without motor

right hehe. about rosak im not so sure lah, but generally all lenses have very good built..juz take care of it.

normally for portrait is a lens with wide aperture.. maybe F2.8, 1.8 or 1.4, because these lens can give nice bokeh (the blur background thing), which usually makes for a good portrait shot. the range shouldn't be too near or far... 35mm, 50mm n 85mm are pretty good range. as u said, if too wide the face can become distorted, making the subject look fat. if too far, hard to get a clear view of ur subject in public places cuz ppl always crossing by hehe. also u cannot use in small rooms

the stretching thing is true. u can see some samples online, most lens review websites got show the distortion. this is only important for certain types of photo lah, e.g. got a lot of straight lines, because it will be obvious when it's distorted. for others, like landscape, etc, shud be ok. fyi all lens got distortion, some worse than the other,but can be fixed in photoshop