Thanks Olaf. I hereby dub thee resident Bismarck Guru and hope you stick around to steer me straight as I honestly don't know much about this ship and am going almost purely on the same 20-30 historic Nazi propaganda photos that are all over the web and the stuff brought up here on the forum! Thank you, and I DO mean it!
That said I know I'm not gonna get a 100% accurate Bismarck and that's OK by me... This one is for me to build new skills and have some fun. I'm trying to get close but will settle for 95% on this build.
So here's my update:
As you might have seen I had a problem sticking tiny metal pieces on plastic without making a mess (Hey, I'm still learning here!

)
After consulting with the works of the pagan model gods I have found the true path now and promptly made use of it to get all the teenie-tiny PE rails onto the main guns (with a quarter for scale):
The secret is tiny amounts of plain old Elmer's white glue... the same stuff I used to make cute paper cutouts for mommy back in grade school. I'd heard the suggestion before and blew it off with a chuckle; surely REAL modelers don't use ANYTHING on their models that isn't toxic, smelly, messy and crazy-expensive... right?
Well, I've changed my tune and am convinced a chemist invented the stuff because he had a hobby that involved sticking near microscopic metal pieces onto to plastic and needed the perfect glue for the job. Perhaps he couldn't find a big enough market before PE so he sold his wonder invention as child's craft glue.

It works,
and how!
I also opened the vents on the front of the turrets; they were molded open but solid.
Here's some photos with paint; they still need weathering and some more assembly, but all and all they are represented very well by the kit with little modification.
... And another shot of a couple of the secondary guns:
I also looted and modded a craft organizer box to keep them safe since this is a LOONG TERM project.
Now my mistakes, so you don't make 'em too! After putting on the rails I noticed the side rails should be lower down on two of the turrets (turrets Bruno and Caesar, I think) That's a mistake that will just have to stay, since it is impossible to get the rails off without ruining them.
The kit gives you the option of putting either the rangefinder "wings" on the turrets or capping them off; near as I could tell all four turrets had them early on (the time I am portraying my Bismarck) but later on turret Anton? had them removed and capped off. Maybe somebody knows what the deal was; Trumpeter didn't give any elaboration on the how or when or which turret had what. It's an important detail to consider if you are aiming for a specific point in time for your Bismarck.
(EDIT 1-2-13 I did some reading and found out the rangefinders were removed on turret Anton in the winter of 1940-41 because they were functionally useless. It seems they were too low and exposed; sea spray would fog them up.)
Finally I spray-painted the PE before installing it (I was having bad memories from the Arizona where the kit PE was so soft you could deform it by looking at it

) but probably shouldn't have; I would have got a more delicate effect had the rails only been painted once. Someday I'll join the 21st century and get an airbrush, but for this project (I'm going for a very clean museum-style build on this one like my Arizona) an airbrush is just a rattle-can that I have to clean afterwards, so I'll continue to wait.