No. Only certain bodily fluids carry the HIV virus, like blood, semen, and vaginal fluid. Casual contact, even contact with other bodily fluids (tears, saliva, etc.) does not pose a great risk of spreading the virus.
It would be highly unlikely to be infected via casual fighting or contacts sports.
HIV is ONLY transmitted through contact with infected blood, semen, vaginal fluid or breast milk. All other body fluids do not contain an adequate amount of HIV to infect another person.
right away
Only if you are going through an outbreak, this is when the sores are discharging and can infect others by contact.
Microorganisms have several avenues in which they can infect larger organisms. They can enter the body through any of the body's natural openings, through wounds or injection and some can even cause infections through skin contact.
Part of the reason is the difference in size. Another is that we consume bacteria but not actually infect them. It is a matter of terminology.
Fungal diseases grow on the organism that they infect. While infecting an organism, they will produce spores that will spread to and infect another organism. Some are able to hang out in the soil (or water, for aquatic fungal diseases) until they come in contact with a suitable host.
Viruses only infect living organisms and since they are not alive, they can not infect other viruses. The question is interesting though.
YES
In that one person is infected by another, then infects a third person, who then goes on to infect another person, yes, HIV is a chain reaction. It is spread through human conctact and transmission of the virus through the blood and body fluids.
No
Yes