Whenever I go somewhere that doesn't have wireless, booting up takes too long when it has to wait for an IP address. Is there a way to set-up a timeout so that the boot process won't take so long? I don't want to have to disable eth1 booting up with the machine.

In gentoo it's possible to change the timeout for this:

* Edit the init script for wireless LAN (should be /etc/init.d/wireless);
* In the function "start()", find the line where the DHCP client (dhcpcd) is started;
* Between "dhcpcd" and the name of the interface, add "-t 10" for a 10 sec. timeout, or whatever timeout you'd like. The default is 60 secs.

Maybe another DHCP client is used in your setup (dhclient, pump), in that case I suggest you check the man pages for those client to see if they also have a timeout option. I only know about dhcpcd myself.