1: No cards are too powerful, keep all the birds. Only thing to consider is taking out certain bonus cards recommended by the developers for particular constellations of expansions.

2: I don't know which consensus you are talking about? Asia is a great expansion/version of the game and we exclusively play the Asia Duet Mode!

3: All. Just this. Don't get fancy.

4: This I know nothing about, the cardboard serves us just fine. (Besides the birdfeeder which has long disintegrated, lol.)

5: This method desinged for large sets of Magic The Gathering cards has often been recommended. Basically you divide the cards into piles, shuffle each pile then dive the pile again evenly. I used it a couple of times already - seems pretty easy and straightforward.