I have some questions regarding the function of the Blocknet.

So I am interested in running a service node which means I need to own 5000 BLOCK.

What is a service node?
I assume it is just an open wallet with 5000 BLOCK in it?

My understanding is that by running a service node you get some BLOCK as an reward which is financed by the fees users need to pay for trading - correct?
How much fees (BLOCK) would I get at the beginning approximately?

In addition to that BLOCK is PoS based. So does that mean that by running a service node I earn BLOCK both by receiving a share of the trading fees AND by receiving the PoS reward which is 9% annually?