In which situation should we concerned HIV?

[missmyexlife]

Dear sir:thin
I come here again.I am lack of knowledge of HIV.and i was feared about HIV ,and i read a lot about it.I used to think that only SEX and  take drugs can resulted in HIV infection.HOWEVER,I read  that needle stick and blood or other HIV  fluids into eyes can also bring HIV.It confused me a lot,I cannot move on and back into my former life.
1,about needle stick,in which situation may it be a hiv concern.NOW i am affraid of sharp objects,i am afraid there is hiv blood on them and they stick into my body....
2,about the eye,its too terrible,i am afraid fluid and if i did not wash my hand i dare not to touch my eyes.
3.there are too may confusions about mucosa,i want to know which  mucosas should be protected?

[Teak]

HIV is transmitted by;
Unprotected penetrative anal and/or vaginal sex
Sharing works with other IV drug users
Mother to child

[missmyexlife]

and 4,about the blood contact.in which kind of contact should be concerned.IF we took a haircut and during it and the shear cut us and if it also cut the last person and the person was HIV infected may this be a confusion.and just like shake hands and we both have wounds on hands....
I am sorry i asked too much ,but i do need your help.
THANKS A LOT!