Welcome!
You should definitely get a cage if you want to get serious about wheelies. Otherwise you will be replacing seats and tail lights frequently.
Clutch ups are much more controllable than power ups, though with some body positioning, these bikes will do power ups pretty easily too. Put your feet and weight on the back pegs and pull up on the bars while giving it some throttle and you will see what I mean.
I can only speak from my experience, but these little bikes are much more fun on the road than sport bikes. My Hypermotard is so fast that I have to be breaking several laws before I start having enjoying it on the road. The Z125 is much more fun because you can wring it out fairly legally. Sport bikes are great for the track, but, at least for me, cramped and overpowered for the street.
I've had other small bikes in the past and loved them, but the Z is more fun than I ever imagined it would be when I bought it. Hopefully you get the same joy out of your Z!