But you have to remember Rory was never good at going solo/being independant. Whenever she's been in that kind of situation she screws it up. (The break from Yale, the New Yorker job offer) so that DOES fit the character it just doesn't fit what lorelai/Luke/Emily/Christopher etc think her capable of, others around her have more realistic expectations of her.
Ditto romantically, she had an emotional affair with Jess while with dean, then slept with dean when he was clearly married (which lorelai called her on) and it took her an entire summer to realise she was in the wrong there, lead Marty on, agreed to a casual relationship with Logan happily dating other guys but hating him dating other girls... She's no saint.
I guessed the last 4 words would involve a baby, circle of THEIR (lorelai and Rory's) life but it could be a boy and 'his name is Rory'.
Clearly the writers see Logan as her Christopher and Jess as her luke. But Logan's too selfish to be a Christopher (Christopher a bit selfish but more weak than decisively so).
As for her age - sadly these days I think there's a lot of immature 30-somethings (which the writers seem to agree with), no clear career focus or family responsibilities. More like 20-somethings of my generation (showing my age 
).
Sookie - producers screwed up! They should have got her involvement secured much earlier, Melissa is incredibly busy and successful I think the most successful cast member? As soon as it was being discussed they should have contacted her, from what I've read and seen in interviews they left it quite late to even ask her.
I agree character wise NO WAY sookie would have left that inn. Writers could have written her in 'invisibly' 'she's in the kitchen/ER/kids are sick' one sided phone calls, one sided 'off stage' comments etc