1. About customizations. Download davinci client (search in internet), than download firmware for w610 from this site's file archive or free from davinci server. )I don't remember if client will offer you to download it for free. Ang yuo need a log for client. I dom't know how much it costs. I think about 5 dollars. What is CID? It's a system that protects your phone from accessing to it's hidden memory. There are many cids and only 51 and 52 are not cracked. For more info searck this forum. If you flash to w610 you'll get Walkman 2.0 and maybe better sound. But will lose active lens cover.