Using the draftwatermark package, you can use a \parbox, or a minipage, to have the text spanning several lines:
\documentclass{article}
\usepackage[a6paper]{geometry}
\usepackage{draftwatermark}
\usepackage{url}
\usepackage{lipsum}
\SetWatermarkText{\parbox{12cm}{%
Mika Ike \\
\url{[email protected]} \\
At My house}}
\SetWatermarkScale{.5}
\SetWatermarkColor{red}
\begin{document}
\lipsum[4]\lipsum[4]
\lipsum[4]\lipsum[4]
\end{document}

In the case of opacity for images, the draftwatermark package apparently doesn't provide many possibilities.
As an alternative, I'd suggest you to use the background package; since this package internally uses TikZ, you can easily control the attributes (opacity, color, position, etc.) for the background material. A little example:
\documentclass{article}
\usepackage[a6paper]{geometry}
\usepackage[scale=2.5,opacity=1,color=red]{background}
\usepackage{url}
\usepackage{varwidth}
\usepackage{lipsum}
\backgroundsetup{
contents={\begin{varwidth}{8cm}{%
Mika Ike \\
\url{[email protected]} \\
At My house}\end{varwidth}}
}
\begin{document}
\lipsum[4]\lipsum[4]
\lipsum[4]\lipsum[4]
\end{document}
The varwidth environment was used to have a box of adjustable width allowing multiple lines of text; a minipage or a \parbox could also have been used instead.

And, using an image:
\documentclass{article}
\usepackage[a6paper]{geometry}
\usepackage[scale=1,opacity=0.75,angle=0]{background}
\usepackage{url}
\usepackage{varwidth}
\usepackage{lipsum}
\backgroundsetup{
contents={\includegraphics[height=\textheight,width=\textwidth,keepaspectratio]{ctanlion}}
}
\begin{document}
\lipsum[4]\lipsum[4]
\lipsum[4]\lipsum[4]
\end{document}

CTAN lion drawing by Duane Bibby.
Mika Ike\\[email protected]\\At My house? Also, one question per post, please.\parbox