To avoid wordpress asking for FTP Username and Password for any upgrade do the following :
Login to your Cpanel
Go to your File Manager
Open wp-config.php and insert the following lines:
define('FTP_USER', 'username'); define('FTP_PASS', 'password'); define('FTP_HOST', 'ftp.example.org:21');
If you want to import blogger site into WordPress you can check simple steps on How to Import Blogger data into WordPress: