Not really.

Not at all.

Definitely not

Actually, not at all.
- no one thought Britney would have a sold out tour again after 2007.
- no one thought she would come back with 3 #1 albums after her breakdown.
- no one thought Britney would be so open to the public with The X Factor.
- no one thought Britney would work with the same producers from Blackout this year. Everyone wanted blackout 2.0 but didn't actually see it coming.

I would also add that her albums each have a distinct sound (sans her first two). You could say her music is a bit unpredictable as well.

No

No

Yes. I didn't think about that. Each album has a distinctive sound to it. She's done something different each album.
BOMT - brought bubble gum teen pop back in the 90s.
OIDIA - stayed teen pop, but sexed up the sound a bit.
Britney - came out of the box with a sexy vibe to her album. Very unpredictable.
In the Zone - experimented extremely with new producers and new sounds. RnB, funk, pop, rock, etc. and blended them together perfectly.
Greatest Hits: MP - the new songs on the compilation had a rock vibe to them with a hard edge to the pop sound.
Blackout - experimented again with new producers and delivered an amazing dance album. Included a song which had the first dubstep influences, 4 years before it blew up.
Circus - more light and fluffy than blackout, but still had a very sexy edge.
Femme Fatale - first artist to bring dubstep to mainstream music. First album with dubstep influences from a mainstream artist.

Nope. She's a trendsetter.

Kind of.

That type of stuff (production) would be credited to the producers.

Yes

No. You never know what her next album will sound like.
She doesn't follow trends, so it's always a bit of a mystery which direction she will take next.

I don't believe so .