Elance.com freelancer.com and odesk.com are currently the top three freelancing websites. I have personally used elance and freelancer and have had decent success finding freelancers there.
However, If you put too many adsense units at the top of your page, Google would penalize you for a bad user experience. Maybe you could test with different combinations and see whether rankings change.
I like the idea. I find it hard looking for trustworthy reviews of marketing apps. If there was one site which i could trust, then i would definitely find myself coming back for more.
That said, there is only one app being reviewed on the site - the site itself. Maybe you could first seed some content yourself and post reviews of apps you use.
Instead of this being a community driven review site i would prefer reviews from a single person or a small team with public profiles. For any marketing app you will find a 1000 fake online reviews. If you can trust into your site, there is a good opportunity here.
You mention that marketing and promotion is not one of your strengths. I.presume none of the 5 cofounders is a marketing guy. Maybe getting a marketing guy on board can bring clarity to the process of bringing customers to your website. Having said that, its not necessary to having a marketing specialist. Make a list of all potential traffic sources - eg googladwords, facebook ads, stumble upon, ads on forums and test them all out to find which works for you.
If you can mention what your business is maybe others here can help you with a marketing strategy