For part one, 10 is the current limit of saved templates. It's possible it can be changed, but in this case we tried to find a balance between average usage and development cost/time. In this case the average recently used (essentially favorites) templates was less than 10 for Auctiva users. With that said we can look into adjusting the value as an enhancement effort in the future.
Part 2, we will be constantly looking at designing and creating new layouts for our templates and new templates in general. Our hope is to continually improve the template system ensuring a great mobile responsive view of your listings, as well as distinct ways for sellers to make their listings pop!