1) This is due to modeling restrictions of okboard that only a-z are supported on the keyboard. They are not special characters, just letters of one or more alphabets, but please remember this is a young project based on Erics own itches primarily and who had specific alphabet(s) without these characters as separate letters and common keyboard letter coordinates in mind. We are though thinking hard on how to extend the model. So meanwhile see it as a way to practice mental training to make curves with fewer keys.
2) It is learning, unless you turned learning off. My experience is that if you type the actual letters for something you curved without a prediction inserted, the next time you make the curves it gives you the alternative.
Please PM any words you think is not showing up even with frequent manual use and your procedure, eg trying only typing not curving etc. It is all about curving.