Ethylene aids in fruit ripening in fruits such as tomatoes. I'd have to do some reading about its effects on cannabis. As with most treatments of this nature, you'd have to already have conditions pretty close to perfect to see a difference. I believe it influences M/F expression too, but how I don't know, and in what direction and to what extent I don't know either.

Yup, you can over-mature lowryder just fine. You could still self-pollinate but then you have another several weeks to wait and I really don't recommend it; instead, start 3-4 seeds a month after your first batch and over-ripen a female from the first batch to pollinate a female from the second.

I'm not a huge fan of ordering feminized seeds. But yes, this technique will work on femmed-seed plants as well.

I also don't know what or how much effect the traditional photoperiod stress would have on an auto strain for making feminized beaners.