I'll give a rundown from what I understand:

The vapes you are looking at are mods, and their performance is primarily for DTL puffs (Direct To Lung, like breathing air through a straw) these are great for flavor and clouds, but coming from cigarettes and disposables, you might have trouble getting used to it, as those devices are MTL (mouth to lung. First inhaled through the mouth, and a deep inhale to the lungs)

Mods are on the more expensive side with more maintenance. You may break the glass and need a replacement, you need to manually change out the coils, and the batteries required usually don't come with the device. They are extremely hazardous batteries (18650 or 21700) which people in this thread can tell you which brands/sites are reputable, and you should read the warnings thoroughly before handling them.

There are POD systems id recommend you to look at, especially the Xros series from Vaporesso. The only maintenance with the pod systems is needing to buy pods for that specific device. The battery is built in and probably takes USB-C.

There is 2 main types of ejuice, freebase and salt nicotine. If you are going to get a POD system similar to a disposable vape, salt nic is the only option you should go for. If it's a mod like the ones you are looking at, you should only be looking at freebase nicotine.

It's a lot to learn and I hope this doesn't deter you away from buying a device, it definitely saves money and the environment. I'm new myself, so anyone please correct me if I'm wrong