I too like to use wire for antennas. As for the Sherman smoke mortar, the late high-bustle turrets like in that Italeri kit had them for sure. Other earlier turrets sometimes had them and sometimes not. Also, some end users modified earlier turrets themselves to add teh smoke mortar. And last but not least, OTHER users (including some post-WW2) removed the mortar and plated over the hole! So there is lots of room for variation.
I've also noticed that no two kits are alike in how they represent this mortar opening; that's fine. There is so much variation in Sherman turret configuration that just about anything is bound to be correct for some vehicle in that 49,000-strong production run...
Greg