your tank is going to cycle regardless... the only way to keep it from cycling would to do 100% water changes EVERYDAY. It can be dangerous for your fish if you put them in the tank and don't monitor the cycle as the levels of ammonia and nitrites can get dangerously high during the cycle. So get a liquid test kit and start a cyclin' ;)
Well that really depends on a few factors but the average is 1-2 months.
What can speed up a cycle is:
1) high bioload.. for instance my 10 gal tank has two male bettas and two mystery snails.. creating more waste= speedier cycle.
2) getting gravel and or filter media from an already established cycled and HEALTHY tank (don't get filter media from the pet store as you don't know what kind of diseases they could have)
3) there are also bacteria cultures you can buy but theres not a very good chance that the bacteria in them are still alive so I stay away from those.
Also live plants are good for cycling and your tank in general but unless you have prior experience with live plants I would wait until your tank is set up just so your not having to learn so many things at once... but then again some people start tanks with live plants and have no problems so its all about preference.
I would recommend cycling a tank that large. You can also get a couple of handfuls of gravel from an established tank and put it in some pantyhose and put it in your tank and that will speed the cycle along.