I don`t think to say „went“ vs „went over“ are verbs to get to worried about. They’re fairly simple. „I went over to my friend`s“ house but but her boy friend went there too. So, I didn’t have much fun because her boyfriend is not a nice guy.“
To say „I went over there“ and „ I went there“ are pretty close in meaning and for the most part interchangeable. The only thing is that „over“ for me throws a sense is distance into the picture. Like I could say „I went over to San Francisco yesterday“ or „I went to San Francisco yesterday“ and there’s not significant meaning in the difference.
You second sentence doesn’t make sense to me so I really don’t know what you mean to say.
The „over“ part really doesn’t add much of anything to the sentence, but people to use it a lot. Sometimes, like I said it sort of puts an emphasis on a bit of a distance, but that’s not a hard and fast rule. I could very easily ask you, „Would you go over and shut the widows (5 feet away) and that’s the same as „Would you go and shut the windows?“ There`s no difference.