Quick answers

Buy chickens to start farming, then convert the eggs they produce into cash. Check your balance after converting before purchasing again.

Yes. The official description says chickens keep laying eggs while you are away. Check the eggs available in your farm when you return.

Merge chickens to unlock rarer ones. Read the merge requirements in your current game before buying extra chickens for that goal.

Read the requirement, reward and any reset warning on the current rebirth screen before confirming.

The official description lists Events, new Gem Upgrades, a new Lucky Block, Gold Chickens, an Obby, a new Rebirth, two new Buy Tiers and balance changes. Check the game panels for costs and requirements.