Is it as simple as using pipe and some "T's and elbows? I had a 3/4 inch line installed in the yard and I need to run three appliances off of it - each with 1/2" fittings. The total BTUs is within the rating for the length and diameter of the line.
You should be ok. I would use1 tee for every appliance and use 1/2" brass tees with it being outside. I would also use copper tubing if you are burying it. You can use black iron, but would need to wrap it with a special tape. You would need to be able to use a flaring tool if you do use copper. Always use liquid dish soap or the likes to test your lines before using, with the line under pressure of course.
I just use a match to test for leaks. If you have one, you'll know right off! Seriously, I would suggest that you hire a professional for gas line work. One mistake can ruin your life in so many ways...