Info on Segwit2x: https://www.coindesk.com/explainer-what-is-segwit2x-and-what-does-it-mean-for-bitcoin/
Alts might go up after the first fork because people might be converting their BTC back to alts. This might be the case, but it's definitely not guaranteed. How long will alts go up? No one really knows. Your guess is just as good as mine. Will the same happen on the second fork? Maybe. But then again, no guarantees.
That is my strategy, trading on the dips, I have more altcoins across the board but they are worth less, after the fork people should, following trends, put their Bitcoin, or at least some of it, back into the altcoin markets - here's hoping