1. Everything in your catalog remains! I do believe you have to relink HHD though to get the large items....
2. I am not completely sure myself but according to past posts and users on TBT, Tumblr, and Reddit "f you're not interested in the map layouts you get for your town, you can turn off the power for your system and reset - your old save will still be there, and you can redo the dialogue again to get a new map. " This is because the game does not delete your town and overwrite until the first save in your new town!
Hope this helps! <3