The length of time you appear at the bottom of the front page depends on how many other new shops open after yours. There are always 3 shown but you can then be found via the see more section.
If you want promotion you must do it yourself. There is lots of helpful advice on this forum about best ways to promote.
You need to make good use of social media and you should set up your social media links against your shop and also make sure you link back to your shop here from social media, eg Facebook.
(I’ve just realised that you have your Facebook link - I’d forgotten it has just moved to the bottom of the page so missed it.
I see that you have an E*** shop and your facebook page points to that. You need also to point to your Folksy shop if you are to be found on here).
The more and better you promote the more likely your shop will be found by all those happy customers out there but unless you tell them you are here they won’t see you, except currently at the top of the new shop list.
Hope this is some help and good luck.
As for how much to list…a full shop looks more enticing than an empty one and the more varied your stock the more chance you have of attractinjg attention.
Joy xx .