Andy_Langton - 5:20 pm on Mar 6, 2013 (gmt 0)
Google doesn't crawl URLs based on directly following links and thus doesn't "enter" the site in any traditional fashion - rather, it finds links and then adds them to the crawl queue (which includes its own priorities for when to grab URLs). Of course, more external links is likely to translate into a higher priority for crawling.
In terms of 301s, most common reason is a crawler asking for a non-canonical version of the hostname, e.g. example.com/page rather than www.example.com/page. Unless you're recording hosts in the logfile they'll look the same.