COMMANDS AND VARIABLES! PLEASE READ THIS!!!

I am trying to make a system that uses one command block and a scoreboard objective called "FIS".

I want to make a loop where it runs a command. I want it to add an item with a data value of 998 if there is no item there, keep the current item there if there is one. Then subtract FIS by 1 and run the command over again. I don't want to have to replace every slot individually. 

If that isn't possible, please make it so that you can add multiple numbers with commas. For example: "..slot.inventory 1,2,4,5,8,..".

And lastly, being able to activate command blocks from commands, most likely the hover note or add another editable part in the command block menu, that can be activated by commands. Mainly for easier easier access.

P.S. Adding a toggle button to decide whether or not it can run out of player chunks would be SO AWESOME!!