Should I build a tool to index public Facebook posts to help customers generate leads ?

I don't know if you have tried this yet, but sometimes having a lookalike custom audience that is 99% similar doesn't always preform better than the lookalike audience that is 97% similar. If I were you I would go through AB test each of the different lookalike audiences, so try 99% vs 98% vs 97% vs 96% vs 95% and see if the less similar audiences will still give you good results, because they should also have a larger audience group for you to market towards. Also have you AB tested interest groups? I'm not sure what your exact niche is but i've worked on campaigns where certain interest groups preformed better than the lookalike audiences. If you're spending a decent amount of money on Facebook ads, having a professional go through and AB test your ads can be a very good idea. It's the difference between having a good ad & knowing you have a perfect ad.

I might suggest starting with Bitly and exploring the possibility of getting a custom branded shortener, which you can set up through Bitly once the domain is purchased. For example, my website is philpallen.com but I shorten all links to philp.al/link so it's more professional. I feel like many other shorteners look like spam, but I'd say your safe with Bitly because it's widely used. A custom one would be even better!

Most of those are very good at syndicating content. Because Facebook doesn't do much in terms of copyright infringement, people can take great content from other places and use it for their own pages. If you do that and include a paid strategy behind it, you have the ability to grow your page quickly.

Of course and have in the past.. With FB's Open graph search you can laser target buyers and weed out tire kickers.. This is a no brainer :)

There are different ways that you can make a profit from a Facebook group. The key is to understand your audience and know what type of services/products they would be interested in. You can charge businesses or companies that are looking to target that specific audience a flat fee and post their products/services on their behalf. You can add affiliate links for products or services that are relevant to your audience and earn commissions on the sales/leads generated from those links. You can sell advertising on a CPC basis. Etc...