I have been speaking with an adviser recently about this same type of topic. He has been telling me that a blog is absolutely key in order to gain attention; somewhere that your users can go to to find out what is going on. Being able to tell someone to go to a link and they can find out more is very powerful, because it creates a sense of curiosity in them that makes them want to go to that link, especially when your pitch is welcoming yet abstract enough to spark the curiosity. It's like telling someone not to push the big red button that says "Don't push."
On the flip side, I think that, as a startup team, we will be pushing an early social media presence. It's sort of the same thing as having that blog page, but it's even more real time and interactive with the user/fan base. It gives people even more content to grasp on to and show their friends. It can create a lot of hype when, again, you have a welcoming yet abstract way to get people to click and even inspire them to show their best friends. After all, word of mouth is definitely the most powerful way to spread something, and there is no better place that word is spread than social media (especially Twitter!!).
I don't believe that my team and I will be running ads. Although you are making more revenue, it creates clutter and a nasty presence when people see it. "Oh man, these people are really just trying to make a few extra bucks. They don't care about their website enough to keep ads off of it, so what makes their product seem any better?" Those are the exact things that I (personally, of course) think when I see an ad on someone's website.
Data points... well installing Google Analytics is a start, and when you get some cash flow coming in you can upgrade to something like Crazy Egg or any other paid web analytics software to get more in depth data. For example, Crazy Egg gives a heat map of where users click most on your page, which that itself shows a lot. Of course there are many more benefits to Crazy Egg, but this is just one of them. I do think that you should factor it in to growth because as you gain more traffic, these analytics tools really show demographics. You can lay out your site to target your target audience better, add more language support, and even find out where to market your product more. These are three key things when working on a startup, for obvious reason.
Of course, this is my input based off of some of the advice that I've received as well as my own experiences/opinions. You have to understand that everyone looks at things differently, and this is what makes things a lot more interested when playing with startups. If it was easy, wouldn't we all be rich?
Hope this helped a little bit, and I appreciate any feedback on what I have wrote (typed?) here, whether it's positive or negative.