There are no Iguanas that 'spit blood'. I think you're referring to the horned lizard - which, as a defence mechanism, has the ability to rupture the blood vessels at the corner of its eyes - shooting a stream of blood at an attacker.
because blood/spit contains cells
If you spit up blood you need medical treatment as soon as possible.
mostly in the tropical rain forest but a few live in islands
They spit blood out there eyes by putting their eyes behind their head and use heat to draw blood out their eyes.
no
Yes, go to the doctor and he will tell you what to do next. Spitting blood is a problem.
yes
If there was blood in the mouth, they would probably spit it out if they didn't want it. They wouldn't do so for any other reason in common legend.
tuberculoses and lung rupture make you cough blood, but pretty much anything that causes you to bleed inside your mouth can cause you to spit blood.
The answer would be no. If the person spit blood into your mouth and you had a sore then YES. Spit will not give you HIV.
Go to a doctor...immediately.
Nicotene does effect blood pressure. But i know of no studies that look at "spit tobacco". Has any one seen any research on this? Spit tobacco has nicotene in it also which raises blood pressure.