The first sentence has no obvious meaning, even when you include "with". However, grammatically, "with" (or "by") is required. "Overwhelmed" is either a past participle or an adjective. It is hard to be sure which one it is, because of the unclear meaning. When we want to show a relationship between a noun and an idea in a sentence, we need a preposition. e.g. I am happy with my job. I am sad about my dog's illness. [adjective] e.g. I was asked about my English level. I am being tested by my teacher. [passive constructions] "Except" and "except for" are both acceptable here. These are bad questions which I would never recommend to a student.