I am so sorry, I didn’t receive a notification of your answers. It’s late, but I’ll answer anyway ^^

Regarding your message to write them back, starting with 先生方 seems wrong because you’re answering to students and 先生 means teacher.
生徒方 is not something I have heard of, and it seems waaaay too strict to address to young people.

Regarding the tone of their message, it’s very friendly and is “slangish” even. まかせろ instead of 任せてください。
If you want to answer in the same vibe, I would simply say: よろしくね＾＾ or something along those lines.
For something more formal: ご協力ありがとうございます would be good IMO.

Note: I am not native Japanese, take my advice with a fistful of salt ^^

In Japanese I would say:

一日終わったら、椅子を重ねてください。