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You should link to your own blog - better for your users and you'll pass some link authority to your blog, which hopefully will then have a better to chance to rank for search terms your main website may not have visibility on.
If nearly all the links of your Blogspot blog just point to your homepage - the value of those links will just be reduced anyway.
I've seen great SEO benefit on linking internally from client's blogs - even if they are not on the same domain.
Interlinking is definitely a factor - but content is what matters.
Take the Disney brands that live on Go.com:
They all live on Go.com but Google surely knows they are really separate sites that cover different topics. Same for any blogspot.com, typepad.com, etc. hosted blog. The millions of blogs there cover a wide range of topics and search engines understand that they are not related just because they share the same host domain.
On the other end of the spectrum - if your site just has two subdomains - let's say www.website.com and blog.website.com ... which cover the same topics and link to one another, search engines would more likely associate those two addresses.
Yes - I believe your blog would look less-biased if it linked out to other useful websites. Some people will say you should "nofollow" those external links so you don't "bleed" your page rank, but I don't think that is beneficial in today's SEO.
That said - try to avoid to any overtly commercial sites that might run competitor advertisements through programs like Adsense. It's a bad habit for blogs to just link to the first site they find through Google searches. It's always better to link to a known brand like NY Times than a low-quality eHow.com type site.
If you have other pages other than your homepage, I would link to the most relevant piece of content you have based on the the context. You don't want to just link to your homepage in each blogpost. The more specific and descriptive you are, the better.