really, dude? Do you know that you can divide one Bitcoin to the 8th decimal place, so if you want to buy 2$ worth of BTC you can do that. Don't call others noobs when you don't know anything yourself
I bought $100 worth of Bitcoin through Coinbase - commission was about 3.8%, which I find reasonable due to the volatility.
Those are all secondary or tertiary listings. Irrelevant largely for the companies as they trade on listed changes in home territories - Danone in Paris etc. You can also buy Americans like FB and GE on European pinksheets equivalents.
Price of something is irrelevant financially. It can be trading at $0.80 or $800, it doesn't make much of a difference except for traders. You don't understand the difference between a listed exchange and OTC, they are very different animals.
There are reports people hack into robinhood accounts a drain them by trading options. I would imagine it would be even easier with pink sheets and bitcoins. I appreciate IB demanding 2 factor ID.