1) only if you as the developers add that Option by plugin or by event script command
2) there is no "perfect" screen size that fits all, because different computers and devices have different displays.
Screen sizes should always be multiples of the tile size to prevent some problems, and minimum map size is the largest screen size implemented.
If the new RPG Maker's character generator produces full busts and can match the art styles of previous RPG Makers, that might be a big incentive to buy it. An easier way to craft custom map tile sheets though would probably be an even bigger game changer.