Probably a generational issue, I used a consultant to set

Probably a generational issue, I used a consultant to set up our website store. The setup was for PayPal Express, which has been working fine.
As a non-profit, I attempted to add Membership2 so that we might generate revenues from people who support our mission. Adding membership types was almost straightforward and I managed to get through that using the instructions. However, setting up the payment gateways was another thing entirely. I do have a degree in nuclear engineering, but I read through PayPal development literature and I am as lost after reading as before I begin. With only single pmt or standard as my PayPal choices, my first googled question indicated that standard was the same as Express. In various forms of documentation one supposedly replaced the other. However, the instruction manual only provides the screenshot of the page and says nothing about how, why, or even explaining things like listening URLs, etc. Moreover, I don't appear to be in the minority when it comes to confusion over this maze. There are people out there as lost as I am.

So here are my questions. . .

1. I have a functional PayPal Express Account. I don't see the need to charging a CC every month for $1 or so to be a member-- so I would be fine with just adding PayPal Single Pay to what I have. Will this accomplish what I seek in Membership2?

2. Given the limited requirement of the single pay PayPal, and since our PayPal account is already live, can I go to the live mode or do I need to jump through all the hoops of setting up a sandbox (which is as unintelligible as anything else from Microsoft (We're Apple groupies)