In terms of specialist tools you need:
Camshaft bar
Crank locking pin
Tensioner locking pin
Eccentric roller pin wrench
You also need a large 1/2" torque wrench for most of the hardware, and a small 1/4" torque wrench which can read in reverse (!) for the eccentric roller. The latter I have found very hard to come by so the alternative is to note the position of the roller before it comes off, set the new one to suit and then measure clearance at the tensioning damper.
General tools you will need metric sockets and 5, 6 & 8mm allen wrenches both loose and in socket-drive (3/8" or 1/2" drive). The 8mm is for the crank locking pin blanking plug, for which you will also need a long extension bar and a universal joint. Tx30 Torx for the water pump and thermostat.
Parts are the full belt kit with rollers and tensioner damper (always do the tensioner damper regardless of apparent condition as it's lifespan is 1.5 belt swaps!), water pump, thermostat, and usually do the aux belt and rollers while I'm in there.
I also recommend a full set of water pump bolts if you can get them (12x N90827702 but they might supercede to a WHT number) and give the existing ones a sharp tap with a hammer via the Tx30 tool before removing to break any stiction.
Bear in mind the OE thermostat (077 121 113C) doesn't come with a seal (N90136802) so that needs ordering separately.
The aux belt is 6pk2680. The aux roller is INA 532006610 and rather than changing the entire aux tensioner (which is expensive and doesn't seem to fail), a roller from a 2.7 Hyundai motor can be used instead
INA 532054310 for that one. You need to use the smaller of the two washers with the centre drilled out, and the original Audi bolt. I recommend the INA version as it comes with the washer you need - others tend to be the bare roller. You save about 60% of the price of the full tensioner doing this
You'll need new coolant too obvs - G13 which is pink / red in colour. Typically about 8 litres for this job, so I use 4 litres of concentrate at a 50/50 mix.