I feel it is on it side because of limit room… but is this incorrectly install?
It’s fine as long as it’s properly supported which it appears to have a support strap attached.
I might question that flue venting though…
I agree with Thomas, I see them quite often without support and write them up because if the bladder fails it can cause damage to the pipes or even to the tank itself.
I also always do a “tap test” to make sure it has an air charge, some inspectors may also check it at the valve.
Yep, if that is a single wall vent, the heat from it could have a negative effect on the tank being so close. They don’t like to it when they get too hot.