Power Messenger does not take up a lot of space on the server. default install is just over 100MB, after you complete the install on the server, you should delete the install_cms folder, this will save some space but should be well within the space requirements of most hosting packages.
Power Messenger contains 100 predefined email templates that you can use a s basis for creating your mailing.
We chose these templates based on the compatibility with various mailing clients. it is impossible to say that they will "displayed correctly in all email clients" since there are still text based clients in use that do not support HTML mailings. these clients will still show the email, but it will be a stripped down, no html version of the email.
yes, you can have multiple administrators managing the emails.
