Let the following sink in, study the data sheet, then most of your questions are answered.
NRF24L01+ packets can be up to 32 bytes in length,
and the optional ACK can contain the same amount.
Nodes can listen to up to 6 addresses at the same time,
each address can be configured to generate an ACK,
and three at a time could also send back data in that process.
There is no limit on how many nodes listen to one address,
as long as at most one, sends back an ACK.
Normal sends request an ACK, which also includes a number of automatic retries,
if no ACK is received.
Sends can explicitly request no ACK, allowing many nodes to receive the same message.
There will be no automatic retries in that case.
Some ideas for your project:
I would not use the network layer for such a simple setup of three nodes.
I would follow a "listen, if you don't have something to transmit" strategy.
If nodes should receive some information at the same time, I would use one address
for this type of information (RX: no-ACK, TX: no-ACK)
I would give each node its personal (+ACK) address, for all the personal data.
I would put all packet data into structs, which allows easy access on both sides.
I would not use any delay(), or other blocking code.