1. Would you try a brand new platform or just pass it up because you're not sure if it's legit or a scam?
That really depends on a lot of factors for me, I mean I pick exchanges because they're trustworthy, have a nice interface to work with and because they have reasonable fees.
Your platform would have to be pretty established before I'd consider using it.
Also, you mention building a decentralized exchange in your title, but your post doesn't seem to indicate this?
2. What other features do you wish was in the existing platforms?
I'm pretty happy with the features in all of the platforms I'm currently using. I'm using Kraken and Bittrex.
3. If you have Tech skills would you be interested in joining in on this venture? ( Will be registered as a LLC )
Sorry, not interested in that.