Simple PCQ (for hotspot)

Hi,

I am not very familiar with the ques, so I have a question. I have a free hotspot (5 APs, with couple of radios) with max 200-300 clients. Total bandwidth is 20Mbit/s. I want to do a simple PCQ based on IP address of the clients.
I am looking at example here:
http://wiki.mikrotik.com/wiki/Manual:Queues_-_PCQ_Examples

First, probably one dumb question. I noticed here for upload traffic, in-interface is ether1 (public), and for download traffic ether2 (LAN). Shouldn’t for upload be, in-interace LAN out-interface WAN, and download from public to LAN?

Second, I want to set PCQ max-limit to 20Mbit/s and PCQ rate to 0, so that total bandwidth is redistributed to number of clients connected. As described here in PCQ rate section:
http://wiki.mikrotik.com/wiki/Manual:Queues_-_PCQ

Question 2: Will this only divide total bandwidth based on number of clients connected, not based on how much bandwidth they are actually using? For example, if there is 10 clients registered, for each client 2Mbit/s is allocated no matter if the client is using it or not. If, 9 clients are not doing any bandwidth consumption, 10th client could not get all bandwidth, just 2Mbit/s that is allocated to it?

If this is the case, what would be que configuration to take in consideration the actual bandwidth consumption of clients, so if some clients are registered, but not using any bandwidth at the moment, this could be used by other clients?