1. Virus scan it and run spyware ad-aware on it - I'm sure you've heard this advice 50 times already so why bother asking?
2. Not technologically, since a link is just a Uniform Resource Locator reference that your browser uses to FIND the file and nothing more. However, using common sense, you can evaluate whether it is likely to be safe or not. Files from domains of large companies like MS, IBM, Amazon etc. are very likely to be safe as they have reputations to uphold. Files from hacker or warez sites are most likely to be unsafe. Files from small personal sites are in the middle in the safety rankings.