1. The order of behaviors isn't particularly important right now, you can just reorder them for organisation.
2. Globals were made event sheet blocks mainly because the new 'local' variables work the same way - for example, you can have a local variable block in an event group, and you can only use the variable in that group. It makes sense to have all variables work the same way, as blocks.
3. You can also right click the event margin, and in the next build 'Add variable' is always enabled in the ribbon. You don't have to scroll down to the bottom.