I am investigating the idea of growing vegetation on desert soil
around Las Vegas, and propose using recycled organic waste from the
city in order to improve the soil quality.

How much should I be able to aquire as raw material, and final
product?(I imagine this figure would be per inhabitant)
How much compost material would it actually provide? - perhaps this
figure could be a figure per square kilometre, at a depth of 1cm.

What else would I have to add to the organic waste in order to make
good soil to grow plants? (I realise that it depends upon the plant
species - but an average would suffice)

Are there any comparable projects I could look at for examples of the
equipment, cost, time etc needed for such an operation?

It appears you are thinking of planting perhaps 6 square kilometers. I
suggest you try several methods at scattered locations, much smaller
scale before making such a large commitment which could fail.
 The county agent of agriculture likely has some information and can
arrange for some soil testing.
 Someone in the Las Vegus sewer or garbage or trash department should
be able to tell you present quantities available, projections for the
next few years, and have some ideas on expanding quantities if you are
willing to pay several dollars per ton for the waste.
 It might even be possible to get the residents and bussineses to
separate matteral that will improve the soil from material that is
nuetral or harmful.
 Sewage sluge has been used for agriculture for at least a century.
Heavy metals in the sluge is the main problem. Some of these are
concentrated in the plants to a level that retards plant growth and
makes the vegetation unsafe for humans and animals. This may be less
of a problem in Las Vegus as there is less manufacturing than in most
cities, perhaps.
 Trash has different problems. Up to half is paper, tree leaves,
stcks, and plastic, which needs to be shreaded very fine, or it
interfers with the plant roots. Shreding will be moderately costly.
Also paper contains significant dioxin, which is dangerious to humans
at one part per billion. Dioxin was likely the principle culperet in
Gulf War syndrom.
 Water use is regulated in dry regions, and yield will be small unless
you irrigate. Well water often has high mineral content that poisons
the soil as soon as the 4 th year of irrigating.
 You can figure about one ton per cubic meter for finelly chopped
trash after it is mixed with soil on the land. Six square kilometers
is 60 billion square cm, so you need 60 billion grams of trash =
60,000 metric tons = 65,000 USA tons of trash to add one cm to six
square kilometers. My guess is one cm is not enough for most plants. 
Neil

You seem to be thinking compost before adding to the soil. Sucessful
compost heaps are about one meter by one meter by one meter with the
composting 90% complete in a few weeks. Obviously you don't want to
wait a few years for slow composting. All the details are moderately
critical and typically it is quite labor intensive. Poor results come
from too much water, too little water, too much leaves, wood, paper,
plastic, sand, too little air.  Too much air dries the pile and
carries away heat. Internal temperature should reach about 136 degrees
according to some experts. Typically the pile needs to be turned =
mixed to get air to parts short on air or soggy with water.
 The only automated success I've heard of is for growing mushrooms.
The same one meter by one meter, by one meter, but "steam" is used to
kill harmful organisms stir the compost, get it up to 136 degrees f
and add the right amount of water. My guess is "steam" is hot water
vapor, tiny droplets of water and air at 136 degrees f   Neil