......How tricky are the inverters to wire up? ......
Physical wiring is easy - just three suitably insulated cores (ideally of equal length) plus really good earth.
Also, if your inverter provides it, make use of their E-Stop.
You do need to be careful, especially when doing the initial wiring, to remember that the capacitors in the inverter can hold their charge for a wee while after the incoming mains power is removed.
Depending on what inverter you've bought, you've then got some setup to do (the ABB ones I use have hordes of parameters!) but many are adaptive and will learn the motor's inductance etc. on their first run.
Key things to watch out for though are setting the min & max speeds for your motor. Max speed for the bearings etc. , min speed for cooling. Many motors have a fan on the end of the shaft, sized to provide sufficient cooling when running at normal mains frequency, but if you run too slow there may not be sufficient airflow.
The inverter itself will need some airflow and possibly forced cooling if its in an additional enclosure.
There's also a chance that the hash from the actual inverter appears on nearby mains and you may just find you need extra filtering (either on the inverter, which can be expensive) or just as a suppressor on the affected computer etc.
Dave