How can this technology, and the data it collects, be used against individuals for purposes such as discrimination? For example, against slower types could be discriminated against.

Do you see this being a centralized service such as through Google so that a profile can follow a user from company to company as well as offline. How do you see that centralization impacting anonymity on the internet? Along those lines, how long has the NSA been using this on us?

I would like to know how typing biometrics handles injuries that affect my typing pattern such as breaking an arm or a finger.

Does this article answer your question, or would you want to know something more? https://blog.typingdna.com/what-if-your-typing-pattern-chang...

So if I switch between single hand typing and two hand typing, I would have to use a different/secondary authentication method?

If the typing pattern is disproportionately different (as it may be the case between switching from single to two hand typing), you would need a fall-back or risk not being authenticated. Or, you could retry typing as you would usually do during an authentication.

So if there are scenarios where you need a fall back, why not just use the fall back?