The oceans on Europa cover a smaller area than Earth's oceans, but they contain a larger volume of water as they're much deeper.

Yes and Ganymede appears to contain concentric layers of oceans separated by layers of ice. There is also Callisto, Encaeladus, Titan, and since New Horizons, potentially even Pluto - not to mention that the trace amounts of H20 present in the sun would outweigh all of it a thousand fold.

Bottom line is that water is never in short supply. Nitrogen is likely to be the real bottleneck in our future efforts at colonisation and terraforming - at least till if/when we master star lifting of resources. At that point, mass and energy no longer make meaningful limiters and waste heat disposal becomes the primary menace to further development.

It's mainly a logistics problem; there's more than enough nitrogen in the Solar system.

We just need to solve the simple problem of moving it from the atmosphere of Venus to where we want it to be. ;)

You're correct in the short term but Venus only has four times the nitrogen content of Earth which might sound like a lot for now but in a fully developed Dyson swarm, will prove to be inadequate. It might turn out to be a non issue since we might be able to simply transmutate it into existence by recycling more abundant materials with fusion but there is still a lot of unknowns with the actual engineering constraints of controlled fusion.

Oh, yes. If we're looking at a future where such infrastructural projects are a thing, then we'll need more nitrogen than we can get from Venus. There's also ethical concerns unless we can completely rule out the possibility of Venusian life.

The nice thing is that we got plenty of time to study Venus since we do not really even need to terraform Venus to colonise it in the short term.

At a high enough altitude, both the pressure and temperature drops to Earth's equivilent. If you have a large enough structure that is relatively airtight (it doesn't need to be perfect), you only need a small temperature gradient to keep it aloft in the upper Venusuean atmosphere.

You could have cloud cities with open air balcony areas where you can walk around with only some basic protective gear and an oxygen supply to protect against the corrosive air and perhaps enjoy gliders or other airborne amusements. It's also good practice for when we decide to attempt something similar with Saturn and some of the other gas giants.