Methods of investigating Fit, Culture, Opportunities, etc. at smaller companies

So you've interviewed with a smaller company, hedge fund, etc. and everyone you met seems great, loves their job, it's a fantastic place to work, etc. How do you really know though if it's going to be a good fit, if what was told you is legit, what are career paths, etc.? Here are some things I would consider - am open to others' suggestions as well. This was originally meant to specifically refer to smaller companies, where there isn't loads of data to review, but feel free to share anything you think is relevant.

- To the extent possible read any feedback on WSO or another career oriented forum (tough with smaller companies due to employees wanting to stay anonymous)
- Read reviews and salary postings on Glassdoor, once again to extent possible. What other sites are good?
- LinkedIn (look at how long employees have been at the company, where they have gone afterwards, etc.)
- Your gut instinct from meeting people, how the job offer process went, how quickly they moved, etc.
- Check the news on any recent developments with the company, lawsuits (current historical), read the 10-k and listen to earnings calls if publicly traded

Any other recommendations?