Question: Does it cost anything to give gift to neighbors or tips to anyone?
Answer: No. You actually get money from the gifts that are used so it is best if you give the "best" gifts.

Question: What are the best gifts?
Answer: Stew. The reason is that you get more coin per plate and more from the overall gift than any other gift. Here is a breakdown of the gifts:

Gifts Plates Coin Total
Roast Chicken 50 8 400
Bacon and Eggs 100 1 100
Stew 150 5 750
French Toast 200 1 200
Waffles 100 2 200

Question: How often can you give a gift to a neighbor?
Answer: Once every 24 hours.

Question: How many people playing the game know that Stew is the best gift to give?
Answer: Unknown. You could always add me though...DOARipper

Enjoy!