Kids made with Steele's genes will always be half-human unless Steele's race or starting race is sufficiently close to the other parent's race; the only example of this exception that I actually know of is that if Steele was originally a half-ausar, their kids with Ilaria (who, despite appearances, is actually an ausar) will be full ausar instead of half. I do agree that this should be explained somewhere in-game, though.
Also, the 'canine' races are only named as such because of superficial resemblances to Earth canid species; they're not actually related to each other.
Not all cock-wielding NPCs can get Steele pregnant, simply because no-one's written it.
Again, this is simply because no-one's written such reactions.
Yes, actually. A milodan TF has been written, but since it has to touch a very important file that's already been ported over to JavaScript, the devs aren't going to code the TF in until the JavaScript port is ready for new content.
Normally, if someone wants to submit a project to TiTS, they write it up in a Google doc and ask for feedback either in these forums or on Discord (unless they're so experienced they don't need to). However, all submissions must be in American English, and given your poor grasp on the language I'd advise you not to try writing for TiTS until you're fluent in English.