yes
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.
If you spit up blood you need medical treatment as soon as possible.
because blood/spit contains cells
They spit blood out there eyes by putting their eyes behind their head and use heat to draw blood out their eyes.
no
No; smoking does not cause urges to spit. However, the smoke taste of a cigarette may cause a person to spit more often.
Yes, go to the doctor and he will tell you what to do next. Spitting blood is a problem.
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.
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.
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.