1. Just make sure when filling you put the hose in your filter compartment so that you "fill" the pumps first to avoid any potential airlock. If by chance you run into any issues when wiring/filing it, your worst case scenario would be to put a "trouble light" in the equipment compartment and a "cattle tank" heater inside the spa to keep the water warm while you fix the problem.
2. how much incline? some manufacturers try to shy people away from shimming especially on the bigger models because a tub that is shimmed has a higher chance for a cracked shell down the road (in most cases, not all)...some companies will even void warranty if certain models are shimmed (if they can prove it of course)
3. fill it up, flip the breaker(s), pour in a metal gon/metal out/etc. etc. if needed, use Taylor K-2006 test kit or take to dealer to test and find your alkalinity ppm out of the tap and adjust accordingly, same goes for calcium hardness (adjusting calcium will depend on your water source as well...ie soft, hard, well, lake, etc.) but your dealer will be able to provide "baseline" numbers so that you can adjust accordingly...once all water parameters are balanced, the next day you should be able to start your chlorine, bromine, silver ion/shock, or whatever system you plan on using
4. good luck :-)