Mine are 15 and 13 now. The 15 year old is in town with his girlfriend, the 13 year old has just rolled out of bed. I asked her if she wanted to do something and I'm waiting on tenterhooks to see if she deigns to grace me with her presence.
My point is this is not forever and at some point you will look back and marvel at how quickly it went. I know that doesn't seem at all possible but it is true.
It sounds like you're doing a great job. No one would be happy getting up at the crack of dawn to tackle constant fights and questions. Unfortunately it is a matter of putting your head down and trying to get through it as best you can.
One bit of advice would be to consciously decide at some point in the day to let go of the schedule and the jobs and just be with them and enjoy them. IME a lot of stress and annoyance comes from the knowledge of what's to come - tiredness, mess, endless hours of nonsense. If you give yourself a break from the future now and again you can breathe for a few minutes and just a few positive moments can make the whole day seem less of a grind.
If they're struggling to get on with each other, modelling/rewarding cooperation can also help. My two used to tell on each other all the time - I told them 'You're supposed to be plotting together against me, not dobbing each other in.' In other words, they should be in cahoots, not working against each other. Even giving them one very small job that they have to complete together to get a reward (e.g. DD pass DS a toy to put in the toybox to get an icecream) can start to build the idea that a sibling is co-conspirator, not a foe.