Wordpress optimization, we will install and optimize the wordpress for better performance. Also do optimization for the site with content, we will give suggestions for speed up the things and with your permission, we will do the optimization for you.
Wordpress Migration, we will migrate the wordpress site form one hosting to the other one. Also do the migration from one domain to another domain. We will handle the dns change also.
Yes, if you provide the necessary login details, I will do the dns changes with minimum propagation delay.
It depends on the environment. I prefer manual installation, since using manual installation, we have full control in the installation and it is easy for us too. If you have any special requirement, mention that too.