On my monitor, the blue doesn't look purplish at all. I'd say it's an acceptable shade here, though I'd have preferred a somewhat less pale blue.
Agreed on the PS.
Shirt collar... well, I believe SB doesn't like button downs. What would you prefer then, a more pointy collar? If his spread collar were less soft and rumply, it would be even less at home with a tweed jacket. So considering the circumstances, it's not bad I'd say.
Jacket doesn't look tight at all. The style of the lapels suggest they didn't have much of a roll to begin with and he's standing with his hand in his pocket. Which, as has been pointed out, is a flapped patch pocket.
There is a sliver of shirt sleeve showing, which is just right. We've gotten used to seeing lots of shirt cuff sticking out, but not so long ago that #menswear quirk would have been frowned upon just as much as on wearing no socks.
FWIW - It doesn't look blue at all on my screen. It appears entirely "purple" and does give off a very out of place vibe for this reason.
I would prefer a different shirt collar because its a tweed jacket. The current collar screams urbanity and clashes with the country styling.
Jacket fit looks ok to me.
I prefer to see more shirt cuff...but everyone seems to fight back against this when criticized for it. It's really looks better when a bit more shirt cuff is seen...this is the single easiest alteration...i think people generally are too lazy and too cheap to take the jacket for altering...and so they all cry out that it is "subjective" or "preference". It's not...its black and white. Looks good or looks bad.