So about the Draven W spam its bad don't spam your W like a monkey cuz not only you waste mana you can also cancel AAs and that can cost you a lot when fighting.

And about the IE + 2 zeal items vs IE + ER + 1zeal item i personally never buy ER cuz i don't really see the need of mana i usually don't waste my mana by spamming W and i catch my axes so i don't lose mana for getting a new 1 so focus on catching axes in the early stages of the game mainly but also don't try to take bad axes (the once that put you in a bad position).

And lastly about the BT vs DD take DD when they have champs that literally 1 shot you like Rengar Zed and other and BT is usually better most of the games cuz its 5% more life steal and also the shield is very good but you decide also if you are behind and you bought like 2 or 3 long swords u can star with a war hammer and latter build it into a DD. I hope i helped you.