I think what you wrote is fine. You could omit "Now" if you like.

I think "might have" is more natural than "could have". I imagine either could be used and certainly your meaning would be clear.

The photograph is not very good quality and appears to contain images of satellites and planets. I would suggest that B is more appropriate because of this. C mentions documents, computer graphics etc, which I don't think the picture depicts, but to be honest, I think it is a rather poor question :) This is one situation where the person asking the question needs to make their question clearer, in my opinion.

Either can be used, but to me "were" feels more natural. When "were born" is used, "born" is some time in the past and to me there is no real "stress" on this. It is also the simpler of the two. With "had been born", to me it stresses the fact that the child was born prior to their death. I am sure some people with stronger grammar knowledge can explain the exact difference for you.

When "whether" is used, I would usually say "whether or not". So "whether" implies a contrast, in my mind. So in your example: He asked me whether I smoked or not. He asked me whether or not I smoked. Some people may not use "whether" this way, but I do. When you use "if", it is OK as in your example. I guess someone could say "if I smoked or not", but to me it is less natural. You could not say "if or not".

There is no real difference except I would say that the first is more natural to me.

Not at all. It is perfectly OK to use "partner" to describe someone you exchange language with. A "partner" is just someone that you have a relationship with. That may be a working relationship, a romantic relationship, a "I will help you if you help me" relationship etc. When the lady you mention wrote "I am married so not seeking a partner" she wanted to indicate that she was already romantically attached and that she was not looking for a male or female to start a romantic relationship. Personally, I feel that it is a little sad that a woman has to write this on her profile. When someone creates a profile on a language exchange site, it should be safe to assume that their only reason for being here is to learn a language. Being a realist, I guess there are those who won't see it that way.

"What attracts me" is correct. For example: What attracts me to your suggestion is the idea that we will both profit. The past tense: What attracted me to your suggestion is the idea that we would both profit. In the above example "would" can be replaced with "could".