Yeah, was kinda two separate things. I want to get story stuff done fast to get some free gear to raise light, but I also don't want to miss out on SRL if it's going away like next week or something.
Also I assume they changed infusing since I last played since everything I've infused went right up to the level of the gear I used.
Yep infusion is no longer some random equation, whatever gear you infused goes to the light level of the gear used in the infusion (you might end up +1 extra light on the deal, not sure how this occurs but I have had it happen).
As for limited, basically anything in The Dawning book that you earn is limited for the life of the event. While strike scoring and such will stay after the dawning, filling in those items in the book and earning rewards from the book will be gone much like SRL (though SRL will be around to play in private matches though again you dont earn progress, just end of private matches rewards).
Luckily, outside of the one Dawning item specifically around the nightfall, all the other strike related stuff is done in any SIVA playlist, meaning the 320 LL one and the heroic (and also nightfall).
Personally I would say grind SRL and when bored, ensure you have the strike bounties and play the 320 LL strike list which should help you get to 365 light. Or the other way around, whatever.
Edit:
Thinking about it, anyone want to do an SRL boosting train? Perhaps help theSlacker make progress as well as others. Me personally I am looking for 1 First Place on Venus and 3 on Mars to finish off my SRL Y1 book...