Check these, please!

[Anonymous]

Hi,
Please check these sentences and correct them.
1. He makes money(,) risking life (and limb).
2. They work for peace(,) risking life (and limb).
3. [Are you risking life (and limb) for a trivial? or Do you want to risk life (and limb) for a trivial?] Don't do that, and tell the truth.
4. I think it would be better if your brother didn't know we are/were here.
5. I find it challengeable [to do, doing] the task alone.
6. I find it pleasant and healthy [to live, living] in the country.
Thanks in advance.

[Pete]

1. He makes money(,) risking life (and limb). [If the second part is essential to the meaning of the first (I.e. he makes money by risking life and limb), omit the comma. It the second part is simply extra information (he makes money, and in so doing, he risks life and limb), include the comma. Also, "life and limb" is a common idiom; if you use the whole phrase, what you have is fine. If you omit "and limb", you should say "his life".]
2. They work for peace(,) risking life (and limb). [I would say to use the comma here. See my note above about "life and limb".]
3. [Are you risking life (and limb) for a trivial? or Do you want to risk life (and limb) for a trivial?] Don't do that, and tell the truth. [See note above about "life and limb". "Trivial" is an adjective and needs a noun to modify: "a trivial cause", "a trivial result", etc.]
4. I think it would be better if your brother didn't know we are/<strike>were</strike> here. [The fact that we are here is fact, not hypothetical, so use simple present.]
5. I find it challengeable [to do, doing] the task alone. [Both are correct. Use "to do" if you are speaking in general (about every time that you do the task), and use "doing" if you are actually doing the task (or have recently done) it - i.e. use "doing" to refer to an actual instance.]
6. I find it pleasant and healthy [to live, living] in the country. [See my note above. If you are now living in the country and are referring to this experience, say "living"; if you are stating a general truth, say "to live".]