It gives you an idea of how likely it is to find something. The majority of SBAs in general aren't high grades, and most of the high grades have been lost as it's not the most popular series and many people just mishandle them or used them etc. The finest ones are incredibly difficult to find and you could easily spend far more buying bags to search and never find one than just buying one. They aren't worth submitting cost wise.
NGC will attribute the Wide Rim and Narrow Rim for free. But, ya got ask for it. https://www.ngccoin.com/submit/services-fees/ngc/ Upon request, NGC examines coins for recognized varieties and assigns an appropriate attribution. PCGS probably does automatically attribute the SBA Wide Rim. They seem to have a few more designations for coins they attribute without requesting attribution. Like reverse B Washington quarters. I see way more of these attributed by PCGS than NGC. I have an NGC unattributed Reverse B. I have spent countless hours searching for an unattributed Reverse B in PCGS plastic and haven't found one. Yet. They don't seem to miss that attribution.
No you don't. Just like you don't have to ask for FB, FBL, FH, PL, *, FS, CAM and so on. It's automatic if they determine that is what it is.