Ah, nice tractor. I just did the full maintenance on mine, thought I'd tell the story...
It is pretty easy. Change all of your filters - fuel, oil, air (you might have two air filters?), hydro. Not sure what the capacity on your tractor is but in my smaller
B7300 there is nearly 4 gallons of hydro fluid. On mine there are two drains for the hydro - need to open both of them to get all the fluid out. You also want to clean the hydro fluid strainer.
Another change you might want to do is the front differential oil. It has been a while since I did that - don't remember all the details but there are a couple of plugs in the front crossmember that you pull to drain and then a fill hole. I think that was gear oil, not sure though.
On my tractor you don't have to do anything special to bleed the fuel system when changing the fuel filter. Takes a bit of sputtering to get it started while it fills back up, though.
I suppose you could disconnect the lines on the front loader to get all the old fluid out. On mine I don't bother but I've changed the hydro fluid regularly so the old fluid in the loader can't be that dirty. It gets cycled through and the small amount of old fluid in there can't have much of an impact on the new fluid's quality.
Have fun with your tractor! I was just admiring the Kubota up at the place my daughter takes riding lessons which may even be the one you have. Great tractor /forums/images/graemlins/grin.gif.