Hi Nima,
Thank you for the suggestions.
We can certainly work on the first 2 suggestions you made. In regard to sending the full voting code to new members by email, this is why there is an email template - so that top list owners can send whatever they would like to their new members. The template already contains the link that the new member should use.
Regarding suggestion number 4 - we currently do not allow members of top lists to hot link banners from the top list domain because of abuse. Members of top lists must save the voting button/banner to their own server to prevent this abuse. I know that when I sign up to a top list, I don't mind saving their button and serving it from my server. Most sites on the internet do not allow hotlinking.
I hope this info helps, and thanks again for your suggestions!