First question. You have to put the multiple sized walls into a .zip file and upload them that way. ONLY .zip, not RAR.
Second question. Projects are moderated and for some reason or other do not qualify to be posted to the gallery. They then will go to your site gallery unless rejected completely. I cannot speak for the moderators as to why your projects were sent to your site gallery, but I wish you much luck in the future and hope you keep working and submitting to WC.