Looks nice! Reminds me of a similar program (a bbs door, really) named ‘yogurt’ by @sedatk — I remember using it to improve my fast-typing around 2002-2003. This brings back memories :)
2. It is possible, and you better believe it. They haven’t updated it, because there is no need for it.
Signal is simply not interested in your messages. It’s also not interested in your metadata, because it’s not an ad platform or a SIGINT front masquerading as a free messaging service.
If all this sounds hard to believe, you should donate.