Propositional Signs

In the Tractatus, Wittgenstein says that propositional signs are signs through which we express thoughts (Prop. 3.12). Does this mean that we need propositional signs in order to express our thoughts, and that such signs constitute a language (or medium of expression) of thought? Are all thoughts propositional in nature? Do propositional signs express or signify thoughts only insofar as those thoughts are propositional? Are there non-propositional signs that express or signify non-propositional thoughts? Do propositional signs themselves constitute propositions or do they merely stand for or signify propositions? Do all propositions consist of propositional signs? Are propositional signs the basic elements or fundamental constituents of all propositions? Is there a proposition wherever there is a propositional sign, and is there a propositional sign wherever there is a proposition? Does every propositional sign have some symbolic purpose or function, and are all propositions symbolic in one way or another?