Deca does aromatize but at only 20% compaired to test. You could get gyno from deca from either the estrogen or progesterone, but at 400 it is very unlikely.
There is a lot of bullshit flying around the boards about Deca causing gyno but I can assure you that almost ALL of these dudes have not done a deca only cycle at 400.
Nolva is best to take is you are concerned about keeping your cholesterol values normal. It has been proven that 20 mg of Nolva per day will help keep your good cholesterol up(HDL)as long as doses of roids are not that high.(ie:above750)
You will not need arimidex at those doses listed.
I would suggest that you take Proviron at 50mg per day with this cycle once the dbol is stopped. Deca, being a strong anabolic and weak androgen will shut down your test production of course, and then you may not have enough androgen in your system to fight off feelings of depression, or at least feelings of wierdness, and sometimes it progresses to deca dick too.
Proviron is also an estrogen inhibitor and the combo of Proviron and Nolva is a classic estrogen fighter.
Proviron is a very poor anabolic but it binds very strongly to the plasma protein SHBG. As a result the strong anabolic nandralone, or any other anabloic for that matter, cannot bind as readily to this protein and thus more of the anabolic is then in the free form state........this equals more gains!
Deca/dbol is a classic stack...good luck and keep me posted.