There is some very good evidence that replacing a manual toothbrush with an electric toothbrush can help in reducing plaque and the risk of gingivitis.
The Cochrane Oral Health Group published a review1 that summarized over 50 studies from 1964-2011. A majority of the studies tested the effects of a rotating oscillating electric toothbrush against a manual ...
The first question I would ask in response to your question on gum disease is "Have you spoken with your dentist about the health of your gums?"
Looking at the NHS webpage on Halitosis, it sounds that most of the possibilities have been ruled out, but not oral hygiene completely.
The most common cause of bad breath is poor oral hygiene. Bacteria that ...
Can 'vigorous' brushing cause dental problems?
Short answer: Yes*
(* reviews tend to conclude that it's better to over-brush than under-brush)
In addition to the good answer by sergiouribe which lists factors relevant to detrimental tooth brushing, there are a few more things you mentioned which are worth dealing with as implicit questions.
A detrimental effect of toothbrushing can be influenced by
use of an abrasive toothpaste
use of hard bristles toothbrush
use of excessive force during toothbrush
excessive number of toothbrushing per day
and any combination of the above
A recent review concludes:
The benefits of normal oral hygiene procedure exceed possible side effects by far, but ...
The quick answer is no, if you want to avoid crowding of the bottom teeth in the futur.
The reason is that the mandible (jaw) is constantly being remodelled, as shown on the picture bellow.
Notice how near the front teeth, who are in a kind of half-circle, the reformation is inward. The diameter of the arch (half-circle) is reduced throughout life, and ...