hey and welcome to the board. well i can tell this is gonna be a long post for me lol! now i acn answer most of these with ways that have worked for me but we should also see what elation says about the best way ot do some of these things.
1) you can assign a fader to adjust the speed of each individual button u have created by right clicking on the fixture page or if u have it in a master scene the master page scrool down till u see live toolbar button. u will see a size and dimmer andspeed button as well. that should work for your qhole page.
2) if it is not doing it in the visualizer but u know it will do it on "real life" then don't worry too much as long as ur 100% sure it is doing what it should be doing. you can also make a profile of the led can on ur own.
3) when u program moving heads or any fixture u have a lot of u can hold down the shift key wilhe u move individual faders and it will to the same to all the same type of fixtures across the board. but to get a inverse pan u go into the constuction mode and open ur fixture folder if u scroll a lil to the right u will see a arrow goin up and down and next to that arrows going left to right check the relevant boxes for the heads u want inversed it should be the box with the arrow going left to right, understand?
4)i know of no way to do this unless u delete them. we will have to wait for elation to respond to that one.
5)you know again im not really sure if this is possible but im sure u can create different sized stage with the same gear and just switch between stages. just make sure you save all the fixture positions once ur done. made that mistakes too many times!! lol.
well i hope this helps and is easy to understand if u have any more questions ask me. best of luck. peace! sincerely jingles!!