Hi. Sorry for the delay. Here are some answers.
Q: Will Scarlet be playing a major role, or will she take a break for the holidays?
A: Scarlet won’t be showing up.
Q: Will Toxx be returning? If so, did he do anything to fix her(?)?
A: Toxx will be back. And like all golems, Toxx is prone to the random error. Some more homicidal than others. Holiday stress, you know.
Q: Are there any plans for future Wintersdays to showcase how each of the races celebrate the holiday differently or has the holiday become mostly homogenized?
A: Right now, we are going to have a centralized Wintersday in Lion’s Arch since the city is a crossroads for all the races.
Q: What made it to be so much like our own (eg. presents, snowmen)?
A: Snowmen and presents were a holdover from Guild Wars 1. Back in the GW1 era 250 years ago, snowmen were servants of the goddess Dwayna and were tasked with making sure the children got their Wintersday presents.
Q: Do humans still do the Dwayna vs. Grenth thing?
A: Yes, but it’s far less pronounced since the exodus of the Six Gods.
Q: Are there any differences in seasons for Tyria, and if so, how does that affect festivals and celebrations?
There are four seasons in Tyria (Zephyr, Phoenix, Scion, and Colossus). The start of Zephyr is the beginning of the year and the end of Colossus closes out the year. On the whole, these seasons are used by NPCs, namely farmers, to sew, grow, and harvest their crops. The seasons have no impact on the festivals or celebrations.