Just trying to give you some advice, but I don't really know how to type in simplified characters so bear with me here lol

我们会去美国所以需要买美金。(so in this case it would be better if you replace "買" with "換" because you don't actually "buy" US dollars, you exchange currency)

我不可以去饭店吃午饭因为我没有钱，可是我可以去明天。( I think you are trying to say that "you are not able to go to the hotel for lunch" , but in this case, you can't translate it directly from English. Would be better if you use "不能" instead. Also, it is not like you don't have money at all, you just son;t have it with you rn, so the whole sentence, in a more logical way, would be like " 我現在(or今天)不能(or沒辦法)去飯店吃午飯(or午餐)因為我沒有帶錢,但是我可以明天去" the grammar of the last part of the sentence is different from English, because in English you say "I can go tomorrow" but in Chinese, you actually switch the verb and the time)

在公交车有多少人？(Because you are "on" a bus, so it would be better to add "上" after "公交車" ( FYI another way to say it in Taiwan is 公車)

你想跟我一起吃晚饭吗？(you can also say 晚餐)

现在我普通话说的不好，可是希望我说话会提高。(I guess you're trying to say I hope I can improve my speaking in Chinese, so it would be more logical to say "可是我希望我能/可以進步"   進步means to improve)

我没有一哪儿睡觉。你知道酒店在哪里吗？( I'm not really sure about the meaning of the first sentence but based on what you said on the second one, I'm guessing you are saying that you don't have place to sleep, so the logical way to say it is "我沒有地方可以睡覺" but if you actually say it this way it would be kind of weird tbh, so you can say, for example,"我今晚找不到地方過夜" which means "I couldn't find a place to crash tonight." And for the second sentence, you can also say "你知道哪裡有酒店(飯店)嗎?" )