Howto set fonts

[Neal Becker]

I want to start emacs --daemon then later connect with emacsclient.

When started, emacs --daemon says:
Warning (initialization): An error occurred while loading 
`/home/nbecker/.emacs':

error: Font not available, #<font-spec nil nil DejaVu Sans Mono nil nil nil 
nil nil 9.0 nil nil nil ((:name . DejaVu Sans Mono-9))>

This comes from setting my default font:
(set-face-attribute 'default                nil :font "DejaVu Sans Mono-9" 
:slant 'normal :weight 'normal)

I get the same message if emacs is started without X (e.g., via ssh).

So really 2 questions:

1.  How to detect if started on a tty and not set font
2. How to subsequently set font if connected via emacsclient.