Some people follow a feeding schedule. The use of liquid fertilizer isn't easy. It's hard to know when to feed and when not to. Best thing to do is use common sense and don't overdo it. I don't think you'll really need the humidity meter. It's more important to create a lot of fresh air in and stale air out. You're going to need something like rockwool or rapid rooters to get seeds started. I don't think you can put them in perlite and get them to grow, but then I've never heard of that so try that if you want. rapid rooters are great because they hold water for several hours. I'd go with a light mix of water and fert, like maybe 1/4 strength that might be recommended on foxfarm feeding schedule and see how that works. Just water at first for a while, get the seeds sprouted and growing and fert some several days later. A flouro light is usually used for sprouting seeds, not mh or hps but you can use those, just don't put them real close to the seedlings. That's all I can suggest for now.