Snakes can sense heat in the RP. So keep it limited to that. It isn't going to confer enhanced tracking or anything like that for the sentient arms, but it does allow them to be aware of sources of heat.
Well, they interact normally with all techniques. There's nothing inherently special about their clashes. So just compete with their damage as you normally would, and they are easily blocked and countered. There is no inherently deceptive aspect to these snakes.
Yes, as a whole they deal a total of 100/120. However, this strength is divided equally between the snakes when you're using them separately, as would any technique.
They are like arms in the sense that they are extensions of you. They can't perform Jutsu for you, or anything like that. You could use them to defend yourself, pick up tools, etc.
No, Power of the Sun is applied to you. It is a Yang fortification that comes from your body. These snakes cannot use Yang Release themselves, or have Power of the Sun applied to them.
Alright that's brilliant, thanks for clearing all that up for me.