That bike you currently own sounds thoroughly abused. My mechanical sympathy makes me sad so I'm going to urge you to learn how to fix your current bike before buying a new one.

All those current problems with that bike can be easily fixed with minimal tools and knowledge. The key is to maintain the bike so that it does not deteriorate to a point where the parts get wrecked. All parts degrade over time without a basic level of care. Everything has a life-cycle.

A wrecked bike is not safe to ride and may cause you harm. You don't really want to collide with a car or tree because you could not be bothered to check your breaks now do you?

You just need time and an interest to learn by watching youtube videos and reading internet posts or talking to your local bike shop.

Mostly the bike does not need much, if any fixing or tuning.

Allow 15 - 20 mins to wipe the bike down. Buy a chain cleaner as these are great for getting most of the crud build up out of the chain as the crud will mix with the chain and wear the chain and gears out. In dry or fairly clean areas you only need to clean the chain every few months. You might find that just wiping it over with a rag will do. You can buy sprays that will 'melt' off most dirt that gets in into the gears if you ride in the mud a lot. After cleaning the chain with chain cleaner, re-apply a light coating of chain oil. Check pads, steering and make sure there is no major wiggle in the wheel as an an-true wheel will rub the pads on pads and even with a disk break the wheel may become un-safe if hitting jumps or going off curbs.

Everything has a life cycle, a beginning and an end. I don't love my bike, I love what it can do and to keep doing what I love to do I have to keep it working.