7.  Is waterproof stucco superior to 
    weather- resistant stucco?

Very rarely.  Why does cement/ conventional stucco work so well?  Because it is not sealed on its face.  It has a concealed barrier beneath almost one inch of cement.  The entire face of the stucco allows water to absorb…but once the rain stops….it dries out very quickly…so water almost never get down to the tarpaper…or if it does get moist…it dries out usually before the next rain fall.  In situations where the stucco is totally exposed like out on a deck or balcony…where the walls are stucco…or on a wood framed chimney…it will be more prone to failure in our North West Rain Forest climate.  This is because it rains so often that ….every rain falls directly onto the stucco…no overhang protection…and wets it deeply…then before it can dry out the next rain comes and wets it even more deeply…and so on and so on ….until it is saturated and then the moisture rises in the wood and then it rots.
Let me illustrate it this way.  You know how you can buy those green scrub pads with a yellow sponge on the back of them.  At Costco…you can buy them in packets of about 5-10.  Each of them come wrapped in plastic.  Normally we tear open the plastic and throw it away.  Now we wet the sponge…probably submerse it in water and then scrub our plate or the counter or whatever….then rinse it under the tap.  If we are done for the day…we squeeze out the sponge and set it beside the sink.  What is like the next day when you go to use it?  Mostly dry….and within 24-48 hours it is totally dry and hard.  Now let's do it another way.  Let's take that same sponge and leave it in the plastic.  Now wash your dishes and your counter with it.  The action of use and movement will break or rip the plastic barrier so that some water gets inside of the plastic packet.  At the end of the day squeeze it out and put it beside the sink.  The next day repeat the process…by now the sponge in the plastic wrap will probably be totally saturated.  Squeeze it out and leave it by the sink till the next day…what will it be like then…in 24 or 48 hours…it will still be wet…in 7 days??..Still wet…in a month??…Still moist and totally rotten.  That is the difference between cement based stucco finishes and waterproof plastic stucco finishes and coatings….the cement just cannot trap water…it will always dry out if given a short time to do so…the plastic coating will trap moisture behind its waterproof coating until it is all rotten.