The site is intended for roleplaying and you can easily introduce what people can do in third person and include it in the way you RP on the site. 

It sounds like you're questioning two separate things?

But for the cards thing I have already suggested a filter for the homepage :) 
https://feedback.worldofpotter.eu/communities/1/topics/991-ability-to-filter-homepage-content

I agree. Being able to sell items would just lead to people selling their gifts and other things when there's no longer use of it.

Putting it up again <3

I think perhaps 5-10 experience per cuddle could be fair considering sending owls also gives 5 experience each :D

As Steven said, it's in the works. My guess is you have to be a little patient with the rest of the books :D

I think a lot of people don't really want others to know. Then there's other (like me) who display it openly or have it on profile. I agree it should be an option to hide if it was to be added.

Although I would love to have more in there, and even wanted to suggest it myself, it will REALLY clutter up the relation tab and that's not the point. If you're VIP you can always put it on your profile :D

It's already planned :3 

https://feedback.worldofpotter.eu/communities/1/topics/554-trade-chocolate-frogs-cards#

Used GTranslate on it, but please keep threads here in English.

Sounds like something you should notify the MoM or HM about though!