Hi Paul,
1) There's basic blog functionality available, whereby you just elect one of your parent categories as the main blog category,
example.
Or you can use the included Wordpress addon,
example.
2) reDUX uses
lazysizes for general lazyloading, so there is scope to use SRCSET in X-Cart, but there's also JSON-LD to encourage Google in the listings.
Don't forget the
image sitemap generator also.
You can PM me your competitors URL(s) and I'll take a look to see how they are doing it.