Basically, I have some shrimp paste, it's a nice, very dark purple colour, and I keep it in the fridge.  It's not "dry", but it's dry enough to be extremely firm when I take some out of the jar with a teaspoon.  I'm wondering how long it will last - since it's mostly salt and is very, very thoroughly cooked when used, I'm thinking it will last quite a few months, but would it last a year? 
Your best bet is a stone ground bread flour or hard flour in the US that means finding a local mill. At your standard supermarket a high protein bread flour is your only option if you can find it there. I generally have to venture out to a Whole Foods market to find that as my "local" grocery store doesn't carry it. You could also try Tipo 00, I have run across it in some specialty stores. You are looking for the highest gluten content you can find so that you can get the elasticity you need to make proper strudel.  