A349: Yes, sizes are standardized in Pathfinder entirely based on size category. However, the Reach does change depending on whether you are Large (Long) or Large (Tall) even though they both take up a 10 ft. space; specifically Large (Long) does not by default have Reach (unless specified in their stablock) while Large (Tall) is assumed to have Reach by default unless otherwise specified). Source.
A350: Yes, Local is one skill. It is used to know "legends, personalities, inhabitants, laws, customs, traditions, humanoids" (Source.). However, I would say there's a strong argument to be made that knowing anything about how things go on in the Feywilds is a Nature or Planes check depending. Still, if your GM is being merciful and taking the skill entirely at face value, I wouldn't complain much. It ultimately is of minimal impact, and I would assume they're ruling for that because it's just simpler that way.
A351: Yes, creatures are ALWAYS flatfooted before their first action in a combat, barring some sepcial ability (eg. Uncanny Dodge).
Direct link.At the start of a battle, before you have had a chance to act (specifically, before your first regular turn in the initiative order), you are flat-footed. You can’t use your Dexterity bonus to AC (if any) while flat-footed. Barbarians and rogues of high enough level have the uncanny dodge extraordinary ability, which means that they cannot be caught flat-footed. Characters with uncanny dodge retain their Dexterity bonus to their AC and can make attacks of opportunity before they have acted in the first round of combat. A flat-footed character can’t make attacks of opportunity, unless he has the Combat Reflexes feat.