As a longtime buyer in both places I do have a suggestion to make: Put the stuff you buy here in a separate library from what you buy at DAZ. Most stuff here does not have smart content entries, and it's easier to sort it by folder than to create smart content. That and it makes it easier to track down when errors occur. That's true for any freebies you pick up also, never put them in the DAZ content library. DAZ allows you to use as many libraries as you want, take advantage of that.

There is a waiting period for initial purchase, I don't recall it being more than 24 hours either. It's more to avoid internet scam artists than anything else, once the account is established it isn't an issue and downloads are pretty quick after purchase, paypal sometimes holds them up for a couple of minutes.

You have as long as you want to download, pretty much as long as you own the account you can re-download anything. There isn't an automatic notification of updates the way there is with the DIM though, you have to go and check periodically to see if there were any changes.