Taking care of the hard drive in my MacBook? Is it bad for my MacBook if I simply close the lid and pack it up? Will this impact the hard drive?

What about using it in a moving vehicle, like a car?
Assuming your computer has a magnetic drive (and not a SSD), when you close the lid, it will take a few seconds for the computer to write some things to the hard-drive; even if it looks fast, it really takes a few secs of “background activity”. It could be 1 sec, but it’s there. 

So as a general rule, it’s always good to gently close the lid (hitting the lid with the keyboard can cause damage to the screen and the hard-drive if it’s too strong), and give the computer a couple of seconds to process the sleep state. Once you’re sure that the box is sleeping, you can pack it up and carry it, always remembering that the Hard-Drive is a mechanical device and as such, it’s very fragile (compared to other pieces). This doesn’t mean that you have to treat your box as if it were Murano glass, but mechanical drives and hits are not friends. With that said, I’ve seen laptops fall from 1 meter (tables) to the floor and work for years without a hard drive failure, and on the other hand, small hits against a table (by raising the laptop 1 cm and letting it fall onto a table) rendered hard drives inoperative. 

So as you can see the drives tend to be more fragile than not, even when you can never be sure. 

I remember about 10 years ago, we were on vacations and for some reason, one of the guys found a box of Sugus candies and we started a fight. Note: They hit really hard and I have pictures of a candy tatooed in my back in red. All in all, one of these candies bounced and hit a guy’s laptop while he was creating a playlist in WinAmp (yeah, we were that old). The computer crashed (Windows XP) and the hard drive never worked again.

The candy story was just a way to illustrate that you can never be sure about hard drives.

Regarding a car: unless you’re going to go to the Camel Trophy, there shouldn’t be a problem. Remember, vibrations and hits may hurt your hard drive, keep it as quiet as possible. 

they guy whose laptop broke still hates us.

I have an old macbook that I carry everywhere, on and off and I drop in bed, I move it, I put things on top of it (books, etc). and it still works…