PayPal Windows 8 Checkout SDK

PayPal Windows 8 Checkout SDK

I was reading the documentation about the PayPal Windows 8 Checkout SDK
for Windows Phone 8 on:
https://developer.paypal.com/webapps/developer/docs/classic/windows-8-checkout-sdk/gs_win8xo/
https://developer.paypal.com/webapps/developer/docs/classic/windows-8-checkout-sdk/ht_win8xo-examples/
Now, I have three questions:
1) Does the API simply redirect the buyer to PayPal's web page on a button
click, from where the buyer can log-into his account using his PayPal
username and password and authorize the transaction?
2) If the answer to question 1 is no, does the API make use of the browser
control?
3) If the API does NOT make use of the browser control, where do you
specify the buyer's PayPal account in the code (see second link)? The code
on the page pointed to by the second link only specifies the merchant's
PayPal account.
Thank you so much :)