PCQ [fair bandwidth sharing] any use behind caching proxy?

Hi,
[This is my first post here, so if i am not in the correct forum please guide me to the correct place for my question.]
My current wireless setup:
User/Client [nanostation5] ------> Mikrotik—> Caching proxy server -----> Internet [aDSL router, 4mg line speed]

I want to share the line speed equally between all online users
For example: If there is only 1 user online he should have the entire line speed [4mg] and if there are 2 users online they should each have half of the line speed [2mg each] and so on, So if there are 10 users online, each will have a 400kb speed.

I am using Squid caching proxy as the proxy server.

I also want to know if i can prioritise traffic AND enable bandwidth sharing?

Thank you

If Mikrotik router is located between client and proxy then yes you can use PCQ to limit client’s traffic.