I am having some issues with my plants (i need to know what the problems are & suggestions of solutions) here is some background:
Outdoor - greenhouse,
Fan blowing 24/7,
low humidity,
gets very hot during day,
past week only 8 hours of sunlight per day rest is in shade (moved now),
occasional flying insects in greenhouse (i kill them when i see them),
soil has very low PH (run off is always much lower than put in),
water via pot (no spray, no bottom feeding (sucking up)),
1 in flower, other 2 still in veg,
all same strain; an auto flower,
for veg giving them all these nutes that have n-p-k : 10.6 - 1.9 - 1.4.
Only just got flowering nutes so until now flowering 1 has been on only water since veg stopped.
1 Previous mite infestation but sorted it & none of these problems were present back then.

Issue 1 :
very light green leaves im guessing this is ok & is just new growth but not 100% as it has a slight yellow in it.



Issue 2:
White residue/stain on leaves; now ive tried too wipe bits off & it takes some doing to get off, so its not very wet or liquidy.


Issue 3: Yellow spots on leaves; im guessing this is some insect/mite problem however i haven't seen any on the plant.


Bud Q: this isn't so much an issue, im more curious as to when i should harvest & how long they look like they have left?
Will they get bigger? Will those white hair looking things curl inwoods & form a proper bud?
When should i harvest? when just over half of those white things have turned orange?

I chopped the top bud off as most of the hairs turned orange i now rekon this was a mistake.

Issue 4: is this sun burnt or a different issue?


Final Q:
Its an auto flower & for the one flowering is it worth chopping big fan leaves off so more light can get to the buds or will this cause the plant to stress too much & thus make it pointless?


Any help with any of them would be appreciated,
Cheers Gr0wC0d3