In English, we use the verb "to be" when forming the present perfect active, all continuous tenses, and all passive tenses. However, be careful not to add "was" or "were" when forming simple past active tense forms. Russian speakers do this quite a lot. When this happens, you accidentally produce a passive verb form. In this case, "drop" can't be made passive and so "was dropped" is meaningless.

Not much. It's not correct. Did you mean 'the wind dropped off'? That means that the speed of the wind reduced.