Just a few comments
Cat5, Cat5e and Cat6 ethernet is only good to 270' (100m). Beyond that, the signal degrades very quickly and by 400' you may end up with too many errors and as usage from all devices on the network goes up, you will have more issues with all devices on your network (not just the long cable).
As stated 400' is not that long for WIFI, with brick and metal that adds some issues to overcome though.
There are 2 common types of directional antennas
1) panel antenna, they are not as powerful but really easy to aim and work better at picking up a weak signal than standard onmi-directional antennas
2) Yagi antenna, they are quite powerful but have a narrow aim.
I did a multi part write up on this topic on my blog
that may be helpful understanding the logic regardless of brand or specific solution.
Writeup
