I'd get a couple gallons, your TA is high and you will fight your high TA for a bit. After you get a feel for your acid consumption, then you can make another trip.
Muriatic Acid does not go bad.
Muriatic Acid (MA) produces a gas that causes rusting in metal parts.
Do not store MA near liquid chlorine
Read this on chemical storage:
www.troublefreepool.com
No. Do not use that. It contains sulfates and will damage plaster, concrete and metals. Use muriatic acid.
Do you have pool math? If not, get it. Use the same login/pw as TFP. Configure your pool volume. Get the subscription...$8/year...allows you to track your tests, chemical additions and share with TFP. Click my username and you can see my logs. After you enter your results, you can click on pH, enter a target and a chemical and it will tell you how much to add. Link-->
PoolMath
Great plan!