Dreaming Wide Awake

That type of bevor seen in the first picture wouldn't usually go with an armet-style helmet, but rather with a helmet without its own built-in neck protection, such as (what is neologically called) a sallet or kettle helm.

If you wanted to get more neck protection out of an armet, you'd use what is usually called a "wrapper plate" which is kind of similar to a bevor but shaped to fit armets.

Arming jackets/doublets (usually also called gambesons - the thing about the Middle Ages is that they didn't actually have a lot of standardized words for things at all and many words we use today to refer to specific pieces of equipment are either completely new, or they refer to something specific today but a medieval person would have used the same word to refer to many different things) have strings all over them not just to keep them tied together but because that's how you attach the plate armor to the body. Their padding also not only acts as padding, but also offers some basic resistance to blades in the event that a blade gets between the plates and through the maille (chainmail) armor that usually fills the gaps between the plates. There is almost no chance at all of a blade penetrating the plates themselves.

Bigger thicker gambesons were worn as a form of armor themselves for poorer soldiers who couldn't afford anything better. They are surprisingly cut-resistant and cushion the body against blunt force as well. Stabbing weapons will go straight through them, but even then it's better to have it than not, because if you're wearing 2 inches of padding and get stabbed by a 5-inch blade in the heat of battle when everyone is constantly moving around and your opponent has no time (or desire) to drive it all the way in, that's only 3 inches deep into your actual flesh instead of 5.

Oh one tip I will give that technically is a correction is that that belt in the bottom-left picture is anachronistic. It's hard to describe how 15th century belts buckle but it usually looks something like this.

Bath tub goddess!! (chubby version!)