To remove the border line go to Appearance -> Theme Options -> Design Options Tab -> Custom CSS paste the following CSS code and Click on save all changes button:
And to change the font you can set via Appearance > Theme Options > Design Options > Typography Options. There you will find to style the font as you like.
I have had a look at Typography options, but does not give option to change font just for block quote, I want the font to be different from content, titles etc.
To change font just for block quote you have to add the cutstom css. Go to Appearance -> Theme Options -> Design Options Tab -> Custom CSS paste the following CSS code and Click on save all changes button:
blockquote {
font-family: arial, serif;
}
Note: Please change above font-family arial to your own font-family.