What is WCF webHTTPbinding from TCP point of view? So - how hard it is from not needed data flow it is? How hard it is in compare to other WCF bindings?
One WCF binding is not any harder than any other WCF binding. That is part of the point with WCF the difference is just in the configuration.
But (there is always a but) some configurations work in some scenarios in which others will not. For example if you are using a Silverlight client, you are restricted in which bindings you can use.
In some case one binding will be "better" than another. For example TCPIP binding is faster than basic http binding, with wshttpbinding you can have encryption, but with basichttpbinding, you would need to use SSL, but that is only point-to-point not end-to-end ....
The binding in WCF configuration describes how the messages will be transported from point to point.
This article describes the basics of WCF, which are basically:
A - the address where the WCF service lives B - the binding, or method of transport to communicate with the service C - contract, or the interface and data types that you will use to communicate with the service