1. I have found source of problem - it was connected with my second issue
logining in at guess checkout reseted shipping and payment methods to default.
So I just swaped those two steps and it solves both two problems
So now its almost ok, but if I set another shipping/payment method than is default and click on this step on button "finish", its just refresh the page (probably save methods change) and I must click "finish" button again to finish order.
And how can I change broswer page title of checkout?
Thank you.
Looking forward to your reply