My experience is that the longer the corks are in the bottle, the easier they are to get out, I suppose because they’ve been compressed longer, and there’s less resistance if the cork isn’t trying as hard to expand back to its original shape.
The bottles and corks can pretty much hold whatever carbonation level you want. My typical rate for a Belgian style is pretty standard 5 oz. (142g) priming sugar per 5 gallons, sometimes a scootch more for Saisons. I also re-pitch some fresh yeast.