2008 Sierra Navigation Install

[gotbass154db1]

I am new to the site so please be patient...I am looking at purchasing the OEM Navigation system for my 08 Sierra. Some concerns i am having include: Do I need to have a Bose speaker system in order for it to work properly? Is GM PART # 19153970 the correct radio for me to be installing? Will my XM and onstar still work after the install (I am very good with car audio..just take a look at my log in name)? The final question is about the JB or JP custom antenna....what is it for? Thank you for checking out my post and i will look forward to checking out some solutions!!