New plant mom here! Help 😭

I have recently moved into a bigger space and in the excitement of filling it up with plants have found myself in over my head 🥲 For context, I live in Dubai, and the temperature outside right now is 42 degrees Celsius with humidity being 38%. It’s very sunny and is like this for 5-6 months in the year. This means all my plants are indoors, in AC for at least 6 hours a day. I water each of them when the top inch or so is dry which is about one a week. Attaching photos of each plant and its problems in the following order –

1. My sad, sad fiddle. This was unfortunately how I got her.
2. Mystery spots on my Birds of Paradise with browning tips. Lots of new leaves with her though.
3. Rubber plant that’s dropped a few leaves and droops a whole lot. New leaves on this one all the time too.
4. Yellowing on my peace Lilly.
5. I don’t know what plant this is but again, drooping and yellowing on bottom leaves.
6. Baby monsterra looking hella wrinkly and sad.
7. My succulent has dropped nearly all its leaves. Can I replant the dropped leaves? What went wrong?
8. This is an IKEA ‘Katy’ that looks like this no matter what I do.

I would love advice on how to help them feel happy and healthier because I’ve only just started my plant journey and already worried I’ve messed up.

Thank you!