Dear bhai
Pleased to see u again 
Ahmad bhai I use apc to wash/ clean such areas , same way as u cleaned engine bay , use some brushes like u can easily get paint brushes from hard ware stores
Use microfiber to dry area and apply grese in necessery areas as apc will washout grese as well and on painted area I use sealants for longer protection , for rubber parts use any tyer dresser even interior detailer will also serve the purpose 