Those are good ideas! In my humble opinion, the two that should be focussed on are:

Customized landing pages by target categories or special news coverage.

I've discovered in my time with gab.ai that having something in common - fitting into a category of sorts - has made me a lot more active than a "general purpose" social network would. Customized landing pages would work.

Offer fan itens with Steem prices to buy.

Swag!!! Everyone sells swag these days. Straightforward as can be!