4. Do you agree that a person who is friendly makes the best colleague?
I agree with the statement that friendly people can be the best colleagues (It would be better to use the plural "colleagues" because "people" is also plural.) in the work place. Here are some reasons to support the idea.
First of all, people who are friendly and have good personalities (or "a good personality") tend to have good relationship with co-workers, so they do their tasks efficiently with helps (This noun is usually uncountable.) from other people, and also they try to help other people as well whenever there is a chance to give a help.
Secondly, they can be your good friends in the office, so whenever you are worried about something and have difficulties; they try to hear your problems and worries. They are good listeners and give you advice.
Therefore I believe, a friendly employee can be the best colleague.