Let's get the easier question out of the way first. When you are confused, you can use about or on, but I think about is the "safer" choice. Behold the ngram.
As for for the taking, let's say that you need a job, and I own a business. I might tell you:
I have a job opening. It's yours for the taking.
I have a job opening. It's there for the taking.
Basically I'm telling you that you could get a job with me, if that option sounds good to you. I could easily substitute "if you want it" for "for the taking".
Looking at the ngram, we see that common ways to use the phrase include
- there for the taking
- free for the taking
- [possessive pronoun] for the taking (i.e., his for the taking, yours for the taking, etc.)
I won't say those are the ONLY way the phrase can be used, but an answer can't delve into every possible usage of a phrase. Those three are a good start.
There's also a relatively high number of
- compensation for the taking
but those come mostly from legal documents; that's not a wording generally heard in everyday conversation.