Someone from the IRC channel responded to a few of these questions:

Q1. It can be an infinite amount of satoshis.

Q2. I had a fundamental misunderstanding of what a micropayment was:
"A micropayment channel allows you to "increment" the amount you have paid them until they redeem it and pay a fee." Yes it could be used for tipping, ideal though is the wrong wording.

Q4. Coinbase and others keep their transactions offchain until they are ready to broadcast.

Q5. This question, too, shows a misunderstanding of micropayments.

Still requesting an answer to Q6.

Q1. How many satoshis can you send in a micropayment channel before it is no longer considered a micropayment?

Q2. Are micropayments ideal for tipping?

Q3. If you have a lot of people tipping a single person, wouldn't that result in a wallet of dust?

Someone recently told me:
"If you want to send small amounts of bitcoin around, your best bet is to use something like Coinbase or Changetip."

Q4. How is using Coinbase and Changetip any different from using bitcoin? Do they get around the fee, and if so, how are they able to do this?

Reference:
https://bitcoinj.github.io/working-with-micropayments

From the above page, there is a statement which makes me wonder how services like Changetip are all able to exists:
"If you send too many transactions too fast, they will get down-prioritised or not relayed by various anti flooding algorithms built into the Bitcoin network."

Q5. How does Changetip get around sending too many transactions too fast if a video goes viral?
Q6. Is the "you" in this statement a single wallet instead of an IP where the service may be running?


I hope this isn't too much to ask!