Pre flower in week 5-6 of veg ?

Normal.

 

Yes that's pretty standard

 

Yep completely natural..... Some do and some don't but most time you do

 

I've found preflowers to be totally random. I've got them on plants that were a week in veg. I've also vegged plants for 3 months and not gotten any. They don't effect when you put the plant in bud either. I let those preflowers continue to veg for over a month and it still flipped to bud like usual.

It's just the plant saying, "Hey, Im female."