are the large boxes (electrical) alonge the side of the road or at buisness ,breakers or power boosters?

Answer 1

Could be any or all three, as indicated in your question.
Transformers to lower or raise the line voltage for specific applications inside the building, phase converters to supply three phase current from single phase supply and last, a master circuit breaker for the supply or transformer primary or secondary.

Answer 2

They can be almost anything from transformers to telephone connections. It may be difficult to tell without opening them.

Answer 3

usually transformers