Learn English – “How much are those jeans?” “which one/ones?”

The instruction as written is clear. "Are to" = must. So you could replace "are to" with "must". Those in wheelchairs must ring the bell. But I would leave it as is.

In your first question, you do not need the for. Examples:

I appreciate your assistance filling out the form.
I appreciate your assistance finding a job.
I appreciate your help cleaning the garage.
Or for a simpler case like the exact one you posted, I appreciate your assistance moving.

If for some reason you really want a conjunction there, you could use in for many cases, but it's not necessary. However, it's worth knowing as many people use it. Example: Thank you for your help in cooking dinner.

In the second question, the order of someone vs. me will depend on what you're trying to convey.

someone in touch with me implies the person you are speaking to told this someone your information and that someone contacted you. me in touch with someone is the reverse: the person you are speaking to gave you the someone's information and you contacted this someone.

It's all about who contacted who: X put Y in touch with Z. To put it another way: X enabled Y contacting Z. X is implicitly the person you are speaking to, ie, "you".