Yeah Decanoate is one of the longer esters.
Using caber on deca is not necessary, your dick and libido will die.
Also until you exceed 300mg test a week an AI is probs not needed.
Aromasin is a suicidal AI, it bonds to aromatase and kills it. If you crash E2 with it it takes longer than arimadex to get back to normal. Only use an AI if you get high estrogen sides.
Dianabol aromatises into 17 methyl estradiol, which is spicier than normal E2, I believe it has a higher binding affinity for E2 receptors.
A dose of 20mgs a day probably wouldn't require an AI, 50mgs probably would.
AAS are tricky to use, they affect everyone differently so my experience may be completely different to yours, on same dose.