Hey everyone, I had a few questions regarding my new snake as I'm a first time owner, I was hoping for some help

So the first thing I was wondering is feeding. I would like to feed him in his terrarium (I know there's controversy over it), but I'm more concerned with substrate getting on the Rat then him swallowing it. I've heard you can put the Rat on a plate (or dangle it over a plate so he thinks its alive) and he'll eat it without eating substrate. Anyways, I'd like to know what y'all have done. Also, the store i bought him from said he was due to be fed cause he hadn't been in 2 weeks, the guy there said he should with no problem. However, i tried feeding him last night and he wasn't even interested, in fact he almost moved away from it which kinda has me concerned (Really concerned). I bought him 2 days ago, and i feared it might be too soon, but hes 5 years old and the guy said he was used to all this so I don't know...
The next thing I would like to know is about his terrarium and if i'm doing it right. So I got him about a 2'x3' tank with Fir and Sphagnum substrate. The only problem I'm having is trying to keep it warm, its sat at 75 the past couple days and he has 2 heat lamps (one red and one white). The red one stays on all the time, and the white one is only on during the day. the humidity is sitting at 55-58 steady. I've tried the wet towel half way over the tank method, as well as spraying the tank, but nothing I do increases it

Is there something I can do to fix this? I also wanted to know if i could add more branches and leaves without him getting annoyed. He has 2 large branches with a half-cut log, but over time I'd like to make a busy-looking habitat that resembles a rain-forest.
Next topic is kinda like the last, its about his water. So I've been using tap water with the drops that eliminate the harsh chemicals like chlorine. Now, I was wondering if i should do it for his spray as well, I did it today with the drops just to be sure before i get responses.
Next thing to ask you nice people, is about handling. So the previous owner works at the store I got him from, and was bragging about how docile he is. I did handle him a bit today and some yesterday (calm and sweet as always), and I asked the guy if he would get stressed and he said "not at all". But I'd like more opinions, he seems like a really sweet snake and hasn't tried to bite me yet. I was planning on handling a couple times a week to ensure he is still used to humans (and because I like spending time with him

) I was also curious if I should move his den (log) if hes in it to handle him, or if i should leave him alone when hes in there (he barely comes out). And all in all, I'd like some tips on how to avoid getting bit

The last thing is his health, I'm pretty sure hes healthy, but i don't know if I can afford to take him to vet visits (Don't know the prices yet). But i wanted to know how to tell if hes sick, cold, or uncomfortable in any way.
My Overall goal is to have him live the longest, happiest life he can possibly have. I'm really excited to have him and I've already gotten attached to him XD (didn't take long at all). And i know most of these things can be found on YouTube, but i like forum responses because i feel you guys are more real and have the experience. Plus I like being a part of the community and hearing what y'all have to say because I imagine you are all snake owners

As I'm sure you can tell, I'm very nervous and want to make sure everything is the best it can be, I just want him to be happy and healthy
Ill attach a pic of him and his terrarium if any of you care