I believe this one expired. These limited time events usually run for a month or so. You get all the rewards you earn. Generally, simply logging in each day and doing all the daily tasks will earn you enough to easily obtain all rewards with several days to spare before the event ends. As for the character, yes, you keep them. If you don’t have the hero yet, they are added to your roster. Duplicates as well, which is good because you will need those to sacrifice and upgrade.