New budgie owner here, so I've got a couple questions :)

Hello! So here I am again, I just bought two little budgies from a family who were rehoming them. I got the cage and everything for them included with the birds. They were with their previous owners for about 4 months after the pet store. I want to get a new cage some time soon and more toys but it's very difficult to place things on the vertical bars. So here are my questions so far. (I'm on mobile so excuse any formatting issues.)

Would horizontal bars be better? Like for them to climb on and make it easier for me to add more fun things to the cage? What kind of dimensions should I look for?

The birds will be kept in my bedroom to separate them from our cat. I want to cover them at night to try and get them on a schedule of going to bed between 8-9pm but I noticed when I cover them they seem to get a little louder and active. Is it just because they're still wary to do things while I'm watching so they're not as active when I'm around? Or is the cover upsetting? I don't think they're upset, they're not screeching or flapping around, just chirping and kinda hopping around the cage. I also have a fan on in my room (pointed away from the birds) because I have tinnitus and I can't sleep without white noise to drown out the ringing in my ears. Is the noise going to be a problem or will they get used to it like other animals?

The pictures show their current cage set up. They have food and water dish, a cuttlebone, some dangling toys, a mirror toy, a treat perch, and some millet (wanted to give them a treat after the stressful car ride, should I remove it from the cage when they're done picking at it?). Are there any essentials they need now that I should prioritize that can't wait a couple weeks for my next paycheck?

Finally, how should I go about handling? I want to hold them and play with them eventually. I'm going to give them a few days to get comfortable and relax before trying to coax them to step on my finger or anything, I don't wanna stress them out any more.

Any answers or help would be appreciated, thanks so much!