A Barracks build spends 20 mana (12+4+4) to get 3 channeling, which is a rather large mana investment early. Therefore it can be vulnerable to rush strats. There are two ways to get a "safe" Barracks start:
1) Watchtower + Sniper in the back, then watchtower + barracks in the front when you can afford them.
2) Barracks in the back, watchtowers in the front, drop Thorg ASAP.
As long as you can get a full-powered Barracks (3 channeling, 4 if Harmonized) without taking a huge amount of damage, you should be in really good shape to win the game. The 'rax can churn out so many creatures so fast, your Warlord just needs to keep himself alive while his creatures Zerg the board. Your main concern is maintaining enough early-game board control to prevent your opponent from simply killing your Mage, your barracks or towers.
Your build looks solid but I would drop the Hands of Bimshalla (They are good for builds with a small number of big creatures, less good for swarms) and pick up two Force Pushes. You never know when a force push will come in handy for re-positioning your creatures. (especially for getting Boltstorm into attack range)
I would also drop one Wall of Stone and pick up a Quicksand. They're really good for controlling big stuff.