Well Im not sure, I've never grown or bred any auto-flowering seeds soley because, In a way I am kinda against auto-flowering strains, they lake the density and potency that I look for.
Not to say they all suck, But I can tell you, most likely you results will vary, bagseed is usually always sativa domn, So if you have a plant that will flower for 100 + days combined with a plant that flowers in 50 days (auto) I'd say you'll end up with a shorter 3 foot plant, that most likely will finish in 75 days or so... But what you can do is, look for the pheno that finishes faster then the others and faster flowering male, breed those two together, and you might bring back the auto-flowering pheno you started with.. But to really get it back you would need to breed it multiple times until it turn consist, so it might be easier to buy more seeds, if that is what you want..
And with the finished seeds, The longer the better, I try to pollinate at around a month into flower which allows 45 or more days, you'll always have unfinished seeds but you can aim for a better % by letting them go longer..
I always say on buds and seeds when you think they are ready let them go another 2 weeks and begin a 2 week flush..