Firstly your asking 2 questions. Answer: NO & Yes
Its NOT necessary but may be DESIRABLE
I dont think I need to explain much more then that

Id like to be but I don't have the discipline when it comes to my diet. I'm good Monday-Friday but cheat on weekends. I can stay around 12 with a little bit of weekend cheats. Really it comes down to your preference if you want to put the time and work into it to stay at single digits.

I like to be about 8% myself. That is where my confidence level is the highest. Right now I am at about 11% I am trying to bulk, but as soon as I hit 210lb (195lb now) I am gonna change diet to cut and get back at 8% at about 200lb hopefully? that's my goal.

I would say no...not really. It all depends on what YOU want to do and how YOU feel about your physique and personal goals/direction/objectives.
I know I got mine into the single digits early this summer...and I did it just for kicks really. Just to see where I could get and how I could get there. To me it was more of another learning lesson in how my body operates by manipulating my diet and all.
I would say if the opportunity is available to you...time and diet takes ALOT of work and MONEY...then go for it. It can't hurt, plus you'll learn something more about how your body loses fat. In all honesty, I think if someone is hovering around 10-12%, then your golden...that's athlete level amount of BF, and just stay around there...that's pretty much what I do.

nothing is necessary, u can be fat if u like, some ppl like a bulky look and some like being ripped, its about preference