Photography

I'm going against the grain and say that pretty much any modern camera can fill your needs, small or big. You say you don't mind packing larger gear, but for travel specifically, you will feel every extra weight.

First, going with modern mirorrless cameras instead of DSLRs will save a huge chunk of volume and weight out of the gate. Though you would be paying a bit extra for modern stuff.
Second, if you're mostly going to shoot in daylight, going with smaller sensor sizes (APS-C or M43 instead of Full Frame) also cuts down weight for the camera body and lenses. If you're really worried about low light photos, then go Full Frame (but I'd say APS-C sensors are still mostly fine).

There is no right way of learning all the ins and outs of photography settings (ISO, shutter speed, F-stop). Digital cameras already make taking photos so much easier, you can learn all those stuff at your own pace. I'd say stop worrying and just go out and shoot. Get a camera that at least has a PASM dial. If you're not sure about what settings for what scenario, put it to Auto/P-mode. Then, you can try out A-mode and S-mode when you need it. Look up stuff when you don't understand a thing, or want to replicate a certain feel. Take more photos, and learn composition along the way. Sometimes composition is more important to a good photo than the right settings.

Hope this helps!

Not what you asked, but you'd be surprised how much of great photography is in preparation, composition and a bit of luck. Don't use the camera as a crutch, it probably takes care of only the small percentage of the result. Maybe go for a course, and learn about the settings on your camera. Yould be surprised at what you can achieve well within your budget. Good luck!

If f-stop and ISO are new to you, don't overthink your purchase. I went to school for photography, and I still use the same almost 20 year old Nikon dslr camera. ANY dslr, with almost ANY lens will get you very far while you learn the terms and what they do to affect your photos. Get a used dslr that has a couple lenses and just start shooting. You will be surprised what 300 bucks on the used market will get you. After awhile, when you get the basics down, then you can invest in some quality lenses. The lenses will make more of a difference than the camera will in most cases. Nikon, Canon and Sony are the big 3 brands, anything from them will be a solid choice.

Personally I've got a Panasonic Lumix G9, I had a G85 until I decided to buy the G9.

NGL I kinda miss the G85 as it was smaller and also had a panoramic mode that the G9 doesn't have. It's also lighter than the G9.

Is the G9 a good camera? Yes it really is.

Do I haul it everywhere for all of my adventures? Also yes.

Was it expensive? So much yes.

The G85 does a lot of what the G9 does, can fit the same lenses, is lighter, is smaller, and is a lot cheaper. Yes the G9 has a higher resolution than the G85 but honestly the G85 is quite pleasant to use.

Plus on the Micro 4/3 system the lenses are a lot cheaper than other systems and you can adapt a lot of lenses to it quite easily.

This isn't what you're asking, but it is what you need to know right now.

If you're having trouble with what DSLR, F-Stop, and ISO mean; You're putting the cart before the horse. It won't matter what camera you get, because you won't know how to use it. The "right" camera for you at this point, will be the cheapest manually controlled digital camera you can get your hands on. Something used, that has an instruction/user manual for you can learn it's specific controls. Then go online and find tutorials about how cameras work generally, and experiment yourself with your camera. Then if you can't get the kinds of pictures you want, do more research about those specific kinds of pictures. After a while, you'll know what your camera isn't giving you, and be able to find which camera will.

Disregard the camera body and figure out what lens system you want to invest in. Your next step should be a crop sensor of some kind as the lens systems for those will be much more affordable than full frames, which will be much more affordable than medium formats. Think Micro 4/3 or Fuji X-mount and the like. Personally I'm a Fuji fan, weather resistant body + lenses that are reasonably portable with better low light performance than micro 4/3 due to the slightly larger sensor

And read the book "Understanding exposure"

If you’re asking this question, I’d recommend a mirrorless (not DSLR). Here are some highly rated models: https://www.dpreview.com/reviews/buying-guide-best-mirrorless-cameras

Digital Photography Review has been around forever and is a wonderful site for learning about options, comparing models, reading in-depth reviews, and getting ranked lists.

Amateur photographer here. I have a lot of advice on this topic, but I'll start with the gear isn't worth shit until you feel limited by it and its capabilities. The problem with gear is that there is a mountain of pressure to focus on buying so much if it. This is by design. All the social medias tend toward this.

I can expand on specific recommendations later when I'm at a computer

There isn't really a universally correct answer here. You need to figure out a budget and what lens focal lengths will work for you. Then maybe people can start making recommendations for you.

Camera bodies will come and go, but you'll want to invest in lenses.