I purchased a Quest but haven't received it yet. My question is can I purchase apps and games now or do I have to wait until I get the Quest. Also, can I download to my computer and if so will it also show on my phone app?
You can go to the store via a browser via the oculus.com website. Go to Apps & Games then click on Quest to get the right ones.
And from there, you can buy things. You'll still have to download them after pairing your Quest to your account.
Beware of something: people new to VR can get motion sickness fairly easily. Games are rated on their comfort level, Comfortable, Modest, and Intense are the ratings, I believe. I strongly encourage you to grow accustomed to Comfortable games before you move on. On the Oculus app store, you can see the rating for each game in the info window right below the "click here to spend your money" button.