I can see that your ties to BC are very strong compared to your ties with Ontario. You can still apply to OINP if you can conclusively prove that if given a nomination, you will move to Ontario and make it your permanent home. Since you are falling short of a few points for your BC PNP and a direct ITA, looks like it is better that you lodge an application with OINP. The drawback here is there is a 1500 CAD processing fee. If this doesn't concern you much, I suggest you can go ahead and try to get a nomination from OINP. Several applicants in the past who have lived in other provinces in Canada have got nominations. Please note that your application will be scrutinized very carefully and the burden of proof that you will reside in Ontario lies on you. You would have to write a compelling intent/reasons to reside letter. You can get a letter of support from your uncle too that outlines how he will help you during the transition phase. You can provide his PP/PR card, DL, rental agreement as proof.
1) There is a possibility, YES! You just need to conclusively that you will move to Ontario if given a nomination. The onus of proving this lies on you.
2) After PT, you have to send them a complete application within 45 days. If you miss this deadline,the PT expires. You will not get a second PT for the same profile. However, you can re-create your EE profile which might again make you eligible to get a PT.
This is only my opinion. The decision, of course, is yours!
Good luck and all the very best!