Correct the sentences with "e.g."

Hi. Please correct these. I think a comma after the abbreviation (is it an abbreviation anyway?) "e.g." is optional. Would you put dots after each letter of the abbreviation "e.g." (like have been done with examples)? Would you do this in formal writing? In what types of writing situations, would you do this?

1. They may be having some difficulties, e.g. find their way to the store to get milk.
2. They can do a lot things while in vacation, e.g. going to an amusement with their friends with their parents' approval.
3. Certain things they have, e.g. bicycles and mopeds, are not high-priced items and certainly they can do without.
4. You can carry it with a lot of things, e.g. bicycles and mopeds.