The third fork is constantinople.
https://www.ledger.fr/category/blog-posts/ From the official site, there's no announcement if they will support those two forks. I haven't received any email from them as notification for those forks.
That's right, and constantinople does not create a new coin. And maybe the exchange will not support when you keep ETH on it.
It's okay to keep your eth on an exchange if you are a day trader as if nothing will happens. I've read some exchange will support these forks as for the constatinople if a fork coin will be generated.