A few questions about Armorer Artificer

1.) If you have, say, plate armor +3, and make it your arcane armor can you still infuse the helmet/gauntlets/boots separately?

2.) If you’re already wearing boots such as Boots of Elvenkind (as basic clothing) and you don your arcane armor which has a Winged Boots infusion, would you get both effects, only effects from one, or is this 1000000% a no go?

3.) Can you only put infusions that specifically state they go on helms into the arcane armor’s helm or could I use infusions that say "a suit of armor" such as Enhanced Defense?