Usually with spider mites you can see them with the naked eye, look for either black dots(adult spider mites) or white dots(juvenile spider mites) usually on the undersides of the leaves. That may only be for the more common two spotted spider mites.If you actually look closely at the two spotted spider mite you can see the two spots on the mites. I don't know about some of the other species of mites, some say rust colored specks...
Often times actual spiders may try to make webs to trap insects that are attracted by your plants(at least in a few of my experiences)
I would say you are safe using the molasses, I've heard it is okay to use from the beginning of flowering up till the end including the normal water only cycles. I have heard it will not help to use it until a certain point into flowering(don't know how long though)but I don't believe molasses will harm your plant even if you started giving it to the plant during veg.
Smell depends on the strain, some are strong, and some are not, I didn't think my last plant smelled very much at all, but it was the first thing anyone who walked into my garage smelled...It could be that you are used to its smell...But could still be a little early to be giving off much smell from the buds.
I would have replied earlier, but I've been having a few problems, one of the clones I got from a friend had spider mites, which spread to my other 3 plants...I tried insecticidal soaps, misting, and finally I let 1500 ladybugs loose in my grow room...There was no sign of the mites until most of the lady bugs died off.(the mite eggs must have outlasted the ladybugs life span). Anyway, I got rid of those plants...cleaned the room out and am starting again...I have a white widow clone, a red dragon clone, and an afghani diesel clone that I plan to use as mothers for my indoor growing(which I am trying my first attempt at hydro) and 4 bagseed that I will be leaving outdoors.(I will probably plant a few more outside when I get some more soil)
Have you transplanted?