Yes, you can use this with your iPhone 4s, but first, you would need something to hold your iPhone, and Amazon sells at least two devices designed for this purpose: http://www.amazon.com/gp/product/B008VI7ORA/ref=ox_sc_act_title_1?ie=UTF8&psc=1&smid=A11V2MDXFAC9IW and http://www.amazon.com/gp/product/B00AAKO646/ref=ox_sc_sfl_title_9?ie=UTF8&psc=1&smid=ASNDEDGSCHLEO.
If the Sony has a standard tripod treaded connection on the bottom then it will fit. BUT, personally I would not use it with that camera as I think this tripod is too light weight and not sturdy or stable enough for it. It will probably work alright for very light use. I use it for a small point and shoot digital camera, my cell phone and a small digital audio recorder and it is ok for them. It is light weight and easy to pack.
Yes. Tripod does allow camera to point straight down (and straight up) nearly 360° with the exception of when pointing down, where the camera lens lines up with elevation lock screw or when pointing up, where handle lines up with tripod leg.