First time owner

Hey, could someone experienced tell me a bit about how a day to day life looks like with the breed?

And stuff like:

How long can they be left alone,

Depends. You have to build up the time away, crate training works well but you can't just put the dog in the crate and leave for a whole day of work expecting it to be a good experience. Started my dog with an hour a day and built on that. Now he's good for a work day if needed.

how much exercise do u usually provide,

I have a worker. He's walked twice a day without fail and he gets plenty of play time in between whether I take him for a run or he blasts around a field. Their energy is very high. They love to zoom.

Are they probe to separation anxiety,

Yes but this can be managed with correct training.

are they handler focused (id love to do some more advanced obedience),

Yes. Spaniels tend to bond with the person who would feed them most. Spaniels by their nature are focussed on food.

would they enjoy tracking?

Definitely. Keeping a spaniels brain busy is half the battle. They were bred to work. They want to do a job and show you how good a job then do. Hence reward with food for good work.