Nice to see someone else growing in a tent under LED lights. I myself have a running tent with ~500W actual power usage on 16 square foot. We might be able to assist each other this winter!
Regarding the buds: It's not unheard of. I would in this case cut them off as soon as possible to reduce apical dominance and get more foliage. The buds after that however, I would probably keep. But to each and their own. If you cut them of you will get more foliage quicker and if you have space, it might be worth it. But it's a controversial subject since it's not really clear what's better. I prefer it personally.
Regarding epsom salt: No, it shouldn't be a problem. Feel free to spray on. Right at budding for fruit production is probably the most beneficial time. Do not do it too often though. I would limit to a maximum of once every 2 weeks, but probably a mean of at least 1 month overall. Also, try to limit to 0.5 % MgSO4 (w/w %) with a very small amount of dish soap (for wetting agent). You really don't need more since this is also a mega-dose, which is the point. At 2 % you might start seeing burn and it's wise to keep yourself from this level with a marginal. 0.5 % is what I do and I've had any problems. Also, do not EVER try to combine this with insecticidal soap. I've got a
thread on here about my stupidity (spoiler alert: it will break both the soap and the epsom salt so neither will work). Also, try to limit the runoff into the soil. Not super important but you don't want to bias the nutrient content of the soil towards ridiculous amounts of Mg (with that said, it will only be a problem at very high levels and you can always wash through the soil if it becomes a problem).
Then I have one final tip. This is completely unsolicited however: Green light. How much do you have? In your picture I can see green but this is from a light source outside of the tent. If you only have the LEDs with NO other light source, does the leaves look almost completely black or not?
Complete lack of green light could be a problem. Why? Because there's phytochromes in the cells (not connected to the photosynthesis) which use excess green wavelengths as a signal to grow in height to overcome a green-filtering canopy. So far so good, what's the problem with no green light then? Guess what happens if you remove this spectrum signal? A completely unintended side effect, a bug if you so wish, can occur whereas there's an "anti-green" effect on the height growth. Effectively your plants might think that there's
not a canopy above them they must overcome, but not really that there's clear sky
either (since sunlight still contains green light). They might "think" that there's an "anti-canopy" above them and basically not grow height at all. A bug in nature since sunlight basically never do not contain any green light, so no selective pressure has prepared them to deal with this.
I got some sources on the green light effect I can give you. I also have Thai Super Chili which reacted on this and produced stacks of leaves all on top of each other. It was ridiculous. No height at all but extremely thick canopy. When moved to green light containing spectrum? They grew height. If you ever think you have this problem you only need to supply a little bit. Say you take them out an hour a day. Or you put in a small white diode or two. You probably do not have this problem but I still wanted to put the information out there. I have a cheap Chinese panel (I do not use in the tent but elsewhere) which has
no green light at all.
Good luck growing!