On documentation

where i can access detailed client service designer documentation that mentioning flow properties and all

Hi @navaneethck_10,

Here is the link below, you can search what you looking for there.
Online Documentation Portal

how i can pass data from a page to node after picking that service as flow of that button ,like i picked flow for the button but now flow needs data so where i will pass the data ?how button will get the data for passing to flow in service

Hi,

After you have picked the flow, the function name of the flow along with its input and output variables, are displayed to the right. You can assign values to the input variables which will be taken as the input arguments for the flow.

You can click the link below to get more details.
Call a Client Service Flow on the Page UI