Congrats on your scope purchase
Firstly, I acknowledge, and agree with what the previous posters have said. So, in summary...
Re what DSO you can see depends a lot on how dark your observing site is and how dark the sky is.
Sydney is generally not a dark site and will provide challenges to seeing those faint fuzzies.
Also, the moon is quite bright at the moment, and will get brighter over the next week. For observing faint DSO, you should wait until the moon is much less dominant, eg around "New Moon" each month.
For moving scope around (in total) you could also explore using a trolley. Iceman wrote an article on how he adapted a trolley for moving his scope around.
Also as suggested earlier, when moving up stairs, it may be best to move the tube separately from the mount. Two trips (or more) but easier on your back.
Re comfort at the scope, I definitely agree, especially with faint fuzzies, the longer you look, the more detail you can extract. I use the Bintel observing chair when travelling to dark remote sites (expensive but effective)
But when at home, I use a gas filled height adjustable stool from Aldi. for under $50.
(I also built a little platform to sit my dob on, that had the advantage of height adjustable legs which can be used to level the scope, which although not essential, can help with smooth movement and locating objects if using setting circles).
Good questions for starters.
But there will be more to come as you develop your skills.