You should execute mount commands in your fstab (/etc/fstab). By the way you run the mount command without declaring any type of file system I would bet it is already in there. This means you just need to change an option in your fstab.
/dev/hda2 /mnt/fat vfat auto,rw,uid=0,gid=500,showexec,quiet,fmask=117,dmask=007 0 0
The 4th option, which I've bolded in the example above, should be set to "auto" if you want it to mount at boot.
To execute other commands add the commands to your .bashrc file in your home directory.