I'm assuming it's down the stairs and getting the barrier removed has something to do with seed trading.  But, as stated in previous topic, I'm unsure as to how to test that/proceeded.  Any help would be appreciated.

If you refer to the barrier that blocks the way to the ruins and is part of the main quest, no these two are not related.

The house is an optional area. If I remember currectly to get inside you needed the ablity to shrink and could also be that it needed to be at night. Not entirely sure, would need to check to be certain.