How do I change Stock Photo color and Place image in AI.

I'm a newbie to Photoshop and it's trying to get the best of me :-)  I downloaded a stock image from sutterstock and I'm trying to change the image color to black and white then place it in AI to " type on line."

1.  How do I change image color to black and white

2. How do I place image in AI - I'm trying to create a postcard.