Yes (encrypted). Feel free to join the discussion in regarding the canonical signatures to help us bootstrap moving key signing to the client side.

Don't store users' keys.

steemconnect v1 can be used to establish this. the tool is already functional in this way.

There's no .NET version of Steemconnect.

Then you will have to wrap it, asking for peoples private keys is simply irresponsible. I use your software but it is no way my recommendation for others to do so. You simply cannot guarantee the security of your system.

There is another much more suitable lib to wrap and that's what we're working on right now.

Steem community needs libraries in as many languages as possible so that developers all over the world could write as many Steem clients as possible.

That I agree with. Nice work on the lib btw!

Sounds risky