Do engineers get their knowledge by playing with electronics
yes or no

No they do not ...
lol

1) Matter is anything except anti-matter, and matter occupies all of everything everywhere. Basically, yes. Unless you see anti-matter, which is doubtful because the anti-matter would implode upon contact with matter, which includes air.
2) The light itself isn't, but it is being emitted by a very hot plasma which is matter.