If you store your grain in a clean dry area and most importantly off the floor you should be alright. Weevils can be a problem if you are milling and leaving alot of dust and debris around. Im sure it depends on location to. I worked at a brewery where we had a minor weevil problem in the box below the mill that fed the auger. We would shop vac it out regularly and the problem disappeared. If you are using only bagged malt it should be easy to inspect. As for storage times it depends on the conditions in your storage area. If there is a lot of moisture you may have trouble. Also if your moisture content in your malt is high it wont last as long. With proper inventory control you should be fine. A small brewery is not likely to be able to negotiate malt and hop prices due to the relatively small amount of suppliers. Out there.
hope this helps.
"You are what you is." FZ