For licensing for a customer (the customer pays you, and you are making the asset available to him for his needs), please look here : https://community.adobe.com/t5/stock/transfer-license-to-a-client/td-p/11990240
For legal reasons, you won't hear from Adobe employees on this subject anything other than pointing to the licensing terms. My disclaimer is just a legal protection of me, as I'm not a lawyer, and I'm not formally trained in legal affairs. But I've written some pretty nice rules for my company, and I've interpreted (c)-law in those instructions. But just in case of, I've asked our IP counsel to look over those rules and to clear them. Normally, they change very little to those rules. I know from the law studies of my wife that sometimes there are precise legal terms meaning something very special to trained persons.
It is also important for me to state that I'm not an Adobe employee, as sometimes people deduct from my status (Adobe Community Professional) that I am. This status is, however, purely honorary, even that it gives your answers on this forum a certain weight.
The Adobe licence agreement, however, has been written to be interpreted by laymen/laywomen, and I think they did an excellent job with that. But yes, I understand that people have questions like yours, as they want to follow the rules.
This said: to your questions A and B: the limit for a print run is 500k, so with max of 30k, you can use the same asset for the same client multiple times. There is also nothing that rules out using the same asset on a flyer, a brochure and a website. You just need to stay under 500k in total for your print run (this includes digital "prints"). For different clients, however, you need to license again. Also for your use you need to licence again, if the asset fits one of your needs.
But to be more precise, even if you violate the terms and print 500k+1, there will be nobody acting for this if it is not a flagrant will fulling breach of the terms.
And for sure there are sometimes (former) contributors who will try to cash-in again with dirty tricks. You have a kind of legal protection via Adobe as a customer, but only if you do not breach the licensing rules.