I try to never use “to be”, because the subject doing the “to being” could be misinterpreted as someone else or the owner. “The column diameter is 650mm” is as clear and direct as I think you should be.
Shop drawing comments and rfi responses are virtually legally binding, so either use imperative forms (use a325 bolts) or declarative statements (bolts are a325). If the contractor misinterpreted the drawings, I generally use imperative statements. If the contractor is asking a question, I go back and forth between the two forms. I think it is overkill to use shall unless you are clarifying the subject performing the work. Generally, the contractor is always the subject of the contract, so referring to them can be redundant. Referring to the contractor too much can also lead to the illogical side effect of giving the contractor room to wiggle out of scope because you didn’t state “the contractor shall”. Furthermore, I try to only say “contractor” when addressing delegated design items, coordination items with entities outside of the contract, safety items, or notifications.
Saying please to me is a matter of your personality. Do what you’re comfortable with. Personally, I don’t use please when directing contract items directly related to the scope in the contract documents or shop drawings, but will use it in correspondence and requests, such as “please coordinate the widgets with the gadgets” or “please see our attached responses”.