because you will be shooting in such low light the camera needs to be kept still so defiantly need a tripod, or you can rest your camera on something but you will have no flexibility composing the shot. also when shooting in low light you need to set the timer or use remote/cable shutter release so you dont shake the camera pressing it.
a wider angle lens would be best suited for this kind of shot i think, but if the 70-300 is all you got then make sure its set to 70mm to get more in.
as for settings... this is were the trial and error in photography comes in. most people shoot in manual mode for this kind of scene with slower shutter speeds and smaller apertures i.e. f/8-f/16 to got more in focus. also make sure metering is set to multi segment/matrix.
theres alot to take into account. which means alot more typing! i would check out gordons DSLR video tutorial on night photography http://www.dslrtips.com/workshops/How_t ... sure.shtml
also this is a good site for tips on various subjects. be sure to check out 'rule of the thirds' http://www.photographymad.com/