Your first question if someone has a relationship with Lord Krsna on Krsnaloka, does he ever fall down? The souls are endowed with minute independence as part of their nature and this minute independence may be utilized rightly or wrongly at any time, so there is always the chance of falling down by misuse of one's independence. But those who are firmly fixed up in devotional service to Krsna are making proper use of their independence and so they do not fall down.
Letter to Jagadisa, 25 April, 1970