みなとみらい
Yes, two words, as seen at the start of this page:
Japanese wikipedia: 横浜みなとみらい21 - Wikipedia
Yes, all one word, as seen on these pages:
Japanese website: http://minatomirai21.com/
English web site: http://goyokohama.jp/
To be serious, though, because it’s Japanese, and you’ll typically see Japanese written with no spaces, writing it in English can go either way, and is a matter of the style of the translator.
Personally, I think Minato Mirai is easier to parse/read in English than Minatomirai. Also consider that みなと means port or harbor, and みらい means the future. Typically a location name made from two words is split in English (unless the second word is “ville” or “burg” or “land” or “dale” or such).
からと
The best I can get is quoting. What throws me off there is where we have simply “と”, and then further we have “「…」と思う”. I think it’s because the first part is more what he felt about the crowd, and the second is more what he actually thought. If we mentally insert 「 and 」, we get:
「たくさんの人で混雑するから」と、花火が終わってすぐ桜木町駅に向かって歩いている
At this point, maybe it can be と言う or と思う, but since there’s a と思う later in the sentence, maybe it’s the same for the first and thus the 思う was dropped?
「たくさんの人で混雑するから」と思って、花火が終わってすぐ桜木町駅に向かって歩いている
This would read as, Because (I felt) it was crowded, we walked towards Sakuragicho Station as soon as the fireworks were over.
Then add on the rest:
「たくさんの人で混雑するから」と思って、花火が終わってすぐ桜木町駅に向かって歩いているとき「来年も一緒に花火が見たい。その時は家族として…」と思い、プロポーズをしました。
At the time when, because I thought it was crowded, once the fireworks were over we headed to Sakuragichou Station, I thought “I want to see the fireworks together next year. At that time, as a family…”, and I proposed.
That’s a bit awkward in English because everything before とき is basically a description of とき (for lack of better wording). In English, I might write it as:
Since it was crowded, when the fireworks were over, we headed to Sakuragichou Station. At that time, I thought “I want to see the fireworks together next year. At that time, as a family…”, and I proposed.
But maybe reworded a little to not have “at that time” twice in English.