99% of the time its simple asexual fission; one cell splits onto two. Rarely (usually in times of famine) the will undergo various forms of sexual merging (partial or complete) and may or may not form spores.
There are no bacteria on other bacteria. Some bacteria do attack other bacteria by piercing their cell wall and injecting proteins. Viruses can attack bacteria. They are called bacteriophages.
bacteria is, unless you were to use the word "The" in front (the bacteria are)
Answer
The bacterium is ...., the bacteria are..... Bacteria is the plural form, bacterium is the singluar.
A sphere shaped bacterium is a coccus, the plural is cocci. Cocci can appear singly, or in twos (diplococci), as a chain (streptococci), or in clusters like a bunch of grapes (staphylococci.)
yes, it depends on the species of the bacteria. Some bacteria can produce toxin to inhibit the growth or kill the other bacteria if the bacteria doesn't have the specific anti-toxin.