1. Closed accounts will continue to age and factor in your credit age, and since the limit will be combined, closing QS1 will have no effects on your score/profile.
2. Since you have already paid the AF on the QS1, personally I would hold off on the combination until upgrading the Platinum to QS first, then roll QS1 into QS. If the next AF is about to hit before that happens, then combine QS1 into Platinum like you originally planed.
3. Are those scores FICO? Since both TU and EQ are much higher than EX, I suspect you're getting TU and EQ from Credit Karma. If that is the case, they're Vantage scores, not FICO.
I'd do things in this order:
The idea behind asking for a CLI before the Steps increase is that particular CLI won't affect Steps. Your Steps increase will preclude any CLIs on that card for six more months.
Definitely try to upgrade the Platinum to a Quicksilver. Start calling in every month once the card is four months old or so.