I use buckets and cups for the first 6 to 8 weeks and then transistion to out side the bins. All the while under the growlights, whether in bins or out. The distance depends for me but no closer than 6 to 8 inches from top to bottom of growlights. I keep a thermometer in the bin and keep it at around 70 to 74 degrees. The Leaves will start to look burned after about two months but that has not affected them when going outside. I go through no light transistion and they go out in full sun. Growth will come to a crawl but thats fine. They are not dying but seem to get use to the light output. I used T5 6400k 8 lights with 8 lights. They have 4 switches which help to control how much light each row may get. Sometimes less is more and you'll be able to adjust. Here is a link that might be useful: Growlights

Not surprised about the Blue Spruce...they are super popular, but prone to disase in many places, and very picky about humidity levels. Unfortunately most fast growing trees are short lived and disease prone. It is sort of a "live fast die young" kind of thing. As other have suggested, Dawn Redwood and Baldcypress are exceptions..fairly fast and disease resistant. Norway Spruce and Eastern White Pine are fast and fairly disease resistant...although, depending on what exactly is afflicting it, they may be vulnerable to the same problems as your spruce. Both would likely be more resistant, particularly the Norway Spruce. And pine have their own borers. Another Tulip Tree is a good possibility, if your current one is doing well. They are pretty fast. Unfortunately I don't think anything in Zone 6 is going to catch up to a 100 year old Tulip Tree in your lifetime...except maybe a hybrid poplar, and those are disease prone. Birch are susceptible to Bronze Birch Borer...River Birch less so then most others. Attractive trees.

There are a lot. The one on the top shelf is a Sunblaster (or SUNBLASTAH as I call it) which is very good if you want one bulb. I have a two bulb fixture below that, both 2 feet. First determine how much area you want to cover and how many bulbs. Then if you need more than one bulb for each shelf and can afford more than one single-fixture light for each shelf, that's a good way to go because you can space them out as needed. I have a four bulb 4' fixture in my basement. I took chances and went cheap with the one's that aren't Sunblaster and they've worked out, but it's a risk. Be sure to read the reviews. If you don't mind purple and blue light, you can search for 'LED grow light' and find a bunch of them that aren't that expensive, but they aren't long like florescent fixtures being square or round.

As mad gallica said, 4’ fluorescent shop fixtures with adjustable height will do fine for starting seeds. I did that for years, starting almost all of my veggie plants that way. 4’ is better that 2’ because the ends have less light than the middle of the fixtures, so more middle space is better. I used chains and hooks for height adjustment. You want the lights hanging just above the foliage, so you need to be able to raise the lights as the plants grow.