FFOF should be fine. Some say it's hot, some say it isnt... for brand new seedlings it could be a little hot, if the plants are already 4 plus nodes in I wouldn't be worried.
FFOF is overall great soil and has enough food in it for 3 to 4 weeks growth, after that you would need to begin supplementing your own.
Also I would be easy with how many leafs you're pulling off. Especially for seedlings. The photosynthesis process they use to grow relies on those leafs gathering co2 and light, it all starts with the leafs.
Some believe in defoliating for better growth and yields but there's a technique to it, it will stress your plant, period. So if you do it you want to do it all at once and not continuously be plucking and dragging it out. I've read of a lot of growers defoliating SOME leafs before flowering, after the plant has gotten fairly bushy, and again around early flower, week 2 to 3.
Some others are not fans of it at all.. a lot of this, as you learn and become more experienced will become your own recipe, whatever seems to work for you and your setup. Until then with this specific topic of defoliating I personally don't think you could go wrong with either technique(taking leafs or leaving them) AS LONG as you don't go too overboard. I made the mistake of taking too many on my first grow that I just finished and it had slowed down growth quite a bit. The reason I bring this up is I noticed you have a seedling that was stripped pretty good.
Less is more buddy
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I hope this helps, good luck