Creating an end user

When I create an end user, it sends the end user an email with the user and password. I have 2 questions regarding this email.

1. How do I get my own email address in the ‘from’ field and not the host email
e.g. show admin@mysite.com instead of accountname@myhost.com

2. How can I change the link in the email from http://www.mysite.com/wp-login.php
to just http://www.mysite.com/

I have a log in drop menu on my homepage. The reason I ask is because I don’t want users going to their dashboard in WordPress. I want them to log into my site and then stay on my site. Is this possible? Thank you very much for your time and assistance.