Usually problems with refillable butane lighters are because they have air trapped in them, and they need to be bled, lots of guides with pictures and such for that online but basically just take a small screwdriver and press the little fill valve until it stops hissing then refill it, do it in a well ventilated place away from sparks and open flames of course

Sometimes that valve is also slotted to make some adjustments and you can try fiddling with that

Yes, they use the same butane as other lighters, it’s not the same thing as lighter fluid in case that’s what you have in mind, it comes in sort of a little aerosol can with a skinny tube sticking out the top instead of a spray nozzle. I’m not aware of any propane lighters out there

Also, in my personal experience, torch lighters just tend to go bad after a while and no amount of fiddling with them will make them reliable again. To be fair I’ve always had cheap torch lighters so maybe that’s just a case of getting what you pay for, maybe nicer lighters are more reliable.