I blog about the development of Tarrasch here. To find out more about the motivation and philosophy of Tarrasch, start with the "About" link on the blog. After that move on to Starting at the Middle which was my first blog post, that one explains why I developed Tarrasch in the first place.
The blog is a good place to discuss and influence the future of Tarrasch. Another place you can do that is the open source Tarrasch repository.
Feature requests are always welcome, but if you are really keen to get your must-have feature into Tarrasch, consider contracting me to develop that feature. It may be cheaper than you think!
And of course you can contact me for any reason at this email address.