Thanks for your questions and for checking out GTDNext! I should note that GTDNext has been around for over five years now. So it's stable and not going anywhere. It's a small team, just @sergio and I running the show. Sergio is the dev and he makes updates to the app as he has time from his main job. This is a passion for us both, but not a full-time gig.
A few answers to your questions.
Not at this time - We continue to make improvements to how GTDNext works on mobile web browsers, but are not planning a dedicated IOS or Android client at this time.
That would be nice, I'll add that to the requested feature list
You can turn any item into an "info" item by setting the"mode" to "info" in the right pannel. This allows you to create outlines of information that will not have task information associated with them.
Not currently in the plans.
This one has been requested fairly often, but has not made it to the top of our list yet.