How many times can you refill your LN channel?
As many times as you want.
What’s the difference between Advertised and non-advertised channels?
Advertised channels are available for routing and are visible on the network graph. Non-advertised channels are not available for routing except for when extra routing information (routing hints) are embedded in payment requests.
How does Buffer capital work?
Buffer capital are the amount of funds that a node must maintain so that during periods of inflow / outflow imbalance the node does not become exhausted (run out of funds).
What is onion routing?
A privacy concept that is archived by each intermediate node only knowing the identity of the previous node and the next node in the payment path.