I've been spending a lot of time recently doing installs of -current from ftp.freebsd.org now that gjb@freebsd.org has a functional builder of head that can be used and tested.
Typically I go to ftp://ftp.freebsd.org/pub/FreeBSD/snapshots/ISO-IMAGES/amd64/10.0/ and grab the latest iso/usb image that is ready.
On my ThinkPads I have to do an MBR scheme to install as the BIOS has a "helpful" GPT installation that assumes *only* Windows can do GPT based installs. 
RootOnZFS#Using_MBR_Disk
The installer in freebsd is ... um ... well, I just flat out don't use it. For me, it is far simpler to just install the laptop from the shell via a few commands after I'm done with the ZFS installation.
Once the system is installed and rebooted, I sync my /usr/src tree to head and run a buildworld/kernel with the following in make.conf:
MAKE_JOBS_NUMBER=8 MALLOC_PRODUCTION=y WITH_PKGNG=yes WITH_NEW_XORG=yes
I have to start with a subversion install first, so I need to portsnap fetch/update
First package to install, every time is portmaster. Then I can track and keep backup packages while I install.
To get X working, start here: http://www.freebsd.org/doc/handbook/x-install.html
More or less, run:
portmaster x11/xorg x11-wm/xfce4, x11/xscreensaver (with extra screensaver options), net-im/finch, security/seahorse, security/pinentry, print/system-config-printer