Giving away your user ID is fine, but you should not give people random URLs that they ask for. Some URLs contain session IDs that can (I think) be used for evil purposes.
The request for account information, before even telling me what they are doing, is what triggered my scam radar. Just a bit more info, I replied to Mr. Chun by email, asking for more info about what they are doing, and saying my identity on bitcointalk.org is private (I don't use the same account name everywhere). I got back the exact same email as in the first post, so it's an automated reply.
Checking their website, it appears to be third party ad referrals. Given that I use adblock on my web browser, I have a poor opinion of ads in general. I don't mind targeted ones on topics I care about, or when I am actively searching for a product, but the rest of the time it's just taking up useful screen space, or even delivering exploits. So I will not only stay away from this guy, but run away and recommend others stay away.
Thanks for everyone's helpful information, I very much appreciate the community here.