macbook pro hard drive replacement

I have a 3rd gen (pre-retina display) MacBook Pro, which needs a new hard drive. I'm considering replacing the hard drive myself. I've done some work on PCs in the past, but never Apple. To help me decide whether or not to tackle this, I have a few questions:

1) Where is a good place to purchase replacement hard drives?
2) Any suggestions on what hard drive to use? I'm not looking to upgrade much, if any.
3) After I've replaced the hard drive, do I have to have a hard copy (CD) of the OS to get it going again? or can it be done without (if so, how)?

Any other tips, suggestions, advice... ?

We need more information about your Mac and which version of OS X it's running.

To answer some of your questions...

1. You can buy a spinning hard drive or SSD from Mac Sales, Amazon, NewEgg, Best Buy, and many other places. There is no difference other than format between drives purchased for a Mac or PC.

2. You need to decide on capacity and price according to your personal needs and budget. Always think ahead.

3. We have no idea which version of OS X you currently have. Any Mac OS X version after Snow Leopard is download only. No CD or DVD.