Welcome back, ! The new wardrobe is still under construction. I'm not aware of any current HA sites, but you can use the "all items" feature to play with wearables you don't yet own (though you cannot actually wear them unless you own them). As for saving, issues can arise if you have too many items on a layer -- but you can buy more layers. :)

It's called a pet leash! If you go to your Pets page and click the pencil-and-paper symbol in the upper righthand corner of the pet you'd like to display, "Leash" is an option in the list that appears. :)

Welcome back, your HA is looking rather striking :D

If you have any other questions, feel free to ask!

Useful Links:

What to do on Subeta? Useful general information for newbies Finding friends (Chit Chat) SubetaLodge (Offsite item database, pet colours etc.)
FAQ