G'day Drew,

In theory, you could use it with the legs collapsed, but the doorways would end up being about 1m high, and you have some issues with excess fabric and tension of the material.
We don't know the roof dimensions specifically, but Darche has previously advised it's around the 3m² mark.

G'day Amos,

Fabric repair tape is the best option, you can find it here.
We recommend putting a strip on both the inside and the outside of the canopy, sandwiching the cut in the middle.

G'day Ryan,

The footprint of this shelter is 4.2m square, so any mesh flooring that is as close to this (or whatever size space you want to be covered) will be suitable.

G'day Stuart,

The Kozi range is brand spanking new, so we have no long-term, or 'in the field' feedback at this stage.
Generally, if you take the proper precautions such as pegging everything out correctly, and maybe adding tracer springs between your guy rope and pegs you should be ok in winds...but keep an eye on things and take the shelter down if things are getting hardcore.
In terms of rain, the shelter has a 600mm Waterhead rating, which technically isn't really waterproof. It may protect you in a lite shower, but I wouldn't be relying on it to keep you dry in any prolonged wet weather.  Ideally it's for shade and UV protection. 
Hope that helps!