1 A stone came flying through the window.
In the combination of the verb to come + ing-form the ing-form describes the way. It it no indication of purpose.
2 In connection with outdoor and similar activites the ing-form is often used after to go/to come as in
A Why don't we go swimming.
B Come dancing this evening, Jane.
C yesterday we went sight-seeing.
(Longman English Grammar by Alexander, paragraph 16.43)
So you have to decide by context whether it is use 1 or use 2. But a stone doesn't
come for a special activity.
Some of us is an indexical expression, which means that it picks out different people in different contexts. Sometimes it includes the speaker, sometimes it does not.
Suppose the speaker is a member of a book club that is debating its next book. Suppose the speaker and two others want to read Moby Dick, but another three members don't. If the speaker utters:
"Some of us want to read Moby Dick."
then he includes himself when using "some of us."
Now suppose the speaker is a member of a book club that is debating its next book, and that three members want to read Moby Dick, but the speaker himself doesn't. Now suppose he is talking to another member who has not yet decided which book they want to read. When the speaker utters:
"Some of us want to read Moby Dick."
he does not include himself when using "some of us."
It is probably the case that when speakers use "some of us" they overwhelmingly more often include themselves than not. (But it is virtually impossible to check this conjecture since corpora do not encode the requisite semantic information.)
Now for some general diagnostics.
When the speaker does not want to include himself, he will often place an emphasis on the "some." For example,
"Some of us want to read a terrible book."
Further, examples where the speaker does not include himself easily take parenthetical remarks which make it clear that he does not include himself. For example,
"Some of us want to read a terrible book (but I don't)."
Best Answer
My advice is don't use it. I think people who use this phrase come across as "try hards". To me they sound like they are trying hard to look cool by imitating a culture they are not part of.
If you insist on using it, you could consider softening it by dropping the "mad" prefix. E.g.
"Props to Andy for winning the hack-a-thon"