using the client script based on the look up filed i wnat to fetch the record details like service number , service rate

using the client script based on the look up filed i wnat to fetch the record details like service number , service rate

based on selected service look up field  iwant to fetch the service serial number in the serice form
how i achive using client script 

also how i get the current date in the date field in the on load of the form