Learn English – After something done OR after something is done

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".

The image is that you are carrying something which needs attention and putting it in front of the listener. So you bring the thing to the listener - or to the listener's attention. In this image, you don't bring the attention to the thing.

The sentence is a bit more difficult to understand because the long noun phrase the unprofessional attitude of one of your staff members has moved from the normal Direct Object position. Because it is very long, the speaker has moved it to the end of the sentence (this is known as heavy noun phrase shift).

If we put the phrases in the normal order, the sentence looks like this:

• I'm writing to bring [the unprofessional attitude of one of your staff members] to your attention.

This last clause has the same structure as:

• ... bring a friend to the party.