If I add someone to the team and I have the premium package do I have to pay per team member for the other members to have use of the premium
features and functions?
If you're referring to Premium, then you can only pay for your one Premium account and can "Share projects" with people who are either free or Premium. If they want their accounts to be Premium, they can of course pay themselves.
If you're referring to Todoist for Business, then yes, adding someone to your team through the Admin panel, will mean that you are going to pay for their account (and every other account you add to your team).
O limite de pessoas em um grupo ou tarefa.
se eu tiver a conta premium posso adicionar 25 contatos que não tem contas premium,
If you have a premium account, you should be able to invite as much as 25 users on a shared project (even if they're a free user). :-)