他這個人做事比較馬虎 馬虎 means like "sloppy", "careless" or "just does the bare minimum". It means that he doesn't really do a great job, he just does it to complete it, but could have done it much better 記下電話號碼 記下 means to make note of something, either written or mental 今天太急了，走路撞到了一個學生 太急了 means that he was busy and pressed for time; in a rush. 撞到了 means that he bumped into someone whilst walking.

No Jeff, “to meet unexpectedly” would not be 撞到， it'd be 遇到 /遇见/碰到, or even 撞见。 撞到 most often takes the literal meaning of physical collision.

撞到 does not mean "to bump into" someone literally but in the figurative sense of "to meet". Better to use 撞倒. Also, this sort of question should be put in the notes section where there are formatting features to show the corrections better.