They look YUM! I think the 60 days they advertise would result in them being harvested before they reach their full potential. My guess would be another 4 weeks.
Unless it is an autoflowering strain it won't flower under 18/6. The pictures aren't particularly clear but it does look like a female preflower. Preflowers will show during veg once the plant is mature, though I haven't often heard of them doing so after 25 days. This usually occurs around 40...
It's normal for lower leaves to turn yellow towards the end of flowering. What is happening is that the plant is throwing all its energy and resources into flowering; stripping them from the leaves. I wouldn't be concerned about it friend.
Well Bloodmeal has a NPK of 11/0/0. I must admit when it comes to fertilizing I do a pinch of this, a scoop of that, so I cannot really tell you how much you need. Not much is needed though.
If the seedling survived they'll probably be just fine. Interrupting light schedules with autoflowering strains is less likely to screw them up. Just put them back under the light.
This is a matter of intense debate. Most will tell you to leave them alone but this is something you will have to make your own mind up about. My recommendation is you trim a plant or two and see the results for yourself. Never remove more than 30% of the leaves in one go as your plant is likely...
If you look after your plant better than the previous grower then it is possible to get better weed than the batch you got it from. The purple is genetic I'm afraid. If the batch it came from wasn't purple before, you won't be able to get it through nurture.
MH is preferable to HPS for vegetative growth. Don't get me wrong, HPS works fine (I use it all the way through my grow) but it will slightly stretch your plant. As for 24/0 vs 18/6 is one of the most debated questions on this forum. Most cannot see the difference in growth rate between the two...