Well, you might be better off staying with the aged domain and use it for SOMETHING. If not, you can do a 301 redirect to tell google and the other search engines the site has permanently moved so you will get SOME of the link juice and PR from the aged domain.

I would do neither unless it's a domain you are desparate for. I would find my own domain name based on the niche I'm looking to enter. Page Rank and traffic are easy to claim if you get it right at the start.

Links won't raise a red flag with google, you will be fine.