Hi - stop watering from the bottom, all you're doing is rotting roots. Water from the top and do it when the top inch of soil is dry unless the soil is literally still sodden from the previous watering, in which case you need a better mix, because FT's do like being watered relatively often compared to a lot of other trees. And stop spraying it - instead, get some kind of tray that's a fair amount wider than the pot, and the tray should have about a 1" rim. Fill the tray with pebbles and water (and make sure there's water there every day, but NOT enough to 'top' the pebbles, a bit less actually because you don't want water wicking into the pot. Then keep the pot on that for humidity, though possibly even in an old large aquarium for better control, though nothing air tight. And give it a couple of weeks to see how it does. What it doesn't need are those heavy pebbles on top - no good reason for them to be on that plant.

I think you might have aphids (watch out for ants who are attracted by them!) and the best (and safest) thing you can do is find some Neem oil at a nursery, either by its own name, or as the major ingredient in a spray made for roses. Soap and water sprays aren't as effective on aphids as they are on spider mites and not always received as well by the plant. Good luck.

Hi - never, ever water by immersion... nature doesn't, so people persist in advising buyers to do it is beyond me (and anyone else remotely knowledgable about bonsai). Water from above when at least the top 1/2" is dry, less often is the rest of the soil is damp or wet (but it shouldn't be if you've potted into a proper fast draining, gritty mix and not 'tropical' or potting 'houseplant' soil. And your tree is not getting 1/10th of the light it needs! Any trop. or semitropical tree needs the highest possible light for up to 16 hrs/day, usually achieved with fluorescent fixtures placed no more than 6" away from the tree.

Remove the moss. Make sure the pots are up on pebbles or something in those trays because they may well be wicking water up to the roots, effectively drowning them (and you're probably watering too often anyhow, except maybe for the Fukien tea). To provide more humidity, trays must be much wider than pots - regular saucers are only to catch 'watering' water. Yellow leaves does usually mean things are too wet, so back off the frequency and let some of the soil dry between waterings. Junipers are outdoor trees, even in Canada, providing they have proper winter protection, so while it's too late now to put yours outside - it'll be shocked by the weather as it didn't go dormant in Nov. thru now gradually - if it's still alive in Oct. I hope you'll have researched how to take care of it then and have somewhere outside to put it. Do put all out in May if at all possible... and I know what you said, but that's why it's a bad idea to buy them before researching. If those pebbles are glued down, get them off entirely so you can see what's going on with the soil... There's no room here for an instant course in bonsai, never mind for 3 trees, so you'll have to do some learning on your own, though whether or not the trees will wait is another story. Very high light is extremely important for those trees, and you need to look at special fluorescents (not just "gro lites") for many hours a day right over their tops or they won't do well at all. Go look at Bonsai4me.com, look at www.bonsaihunk.com, evergreengardenworks.com for starters, and then go to http://ibonsaiclub.forumotion.com (terrific forum with experts and much more activity than here).