Trimming.

Cut them off!

You can if you want to, but you can also leave them if you like too. They are not getting blocked by much as you have a rangy lookin sativa dom strain there im guessing so i see good light pen already, and anyways if you wait a few weeks she will end up pulling nutes from these leaves and they will yellow anyways so id wait til then and then snip em off. maybe the very lowest one that looks like it might touch the substrate and you dont want that. but yeah leave the rest for now if you like.

I would go ahead and trim them off... they're not going to give you much and no, it won't stress the plant out to lose that little bit. Plants in their flowering stage are much stronger and can tolerate a lot more than they can in their vegetative state... in veg, the plant will try like hell to heal the wound but in flower, it's concentrating on getting those flowers bigger and better. If you were talking about a whole LOT of weak looking flowers, I'd urge caution - but this? I'd say let her rip!

Yes you can this is actually a well-known practice called" pruning" and it's actually done about 2- weeks into flower, so your right on time, and no it won't cause any stress to your plant.

Sure can and without any negative effects.

It looks like you have already removed a lot from your plant. Because it is now so open I would leave the lower buds since it looks like they will get a lot of light. If you had left a dense canopy in place I would consider removing the bottom buds but in your case I would leave them.

Yes you can remove the lower leaves to clean her up. You shouldn't remove more than you have to and you can even take a few leaves per day to reduce the stress caused.

What do you mean? Take of the underdeveloped growth to promote growth on the top? I don't follow if that's not what u mean. If it is, then yeah that's fine to do. Ppl do it in a scrog all the time. Sure I only did it to my zkittlez hydro last night and took new unmatured growth to help stim current growth. Happy growing.