Measurements are a guide and for the belt you wont the angled corners to match the belt, for centurion as per the CRL: The corners of the plastic ammo belt shall be trimmed at a 45 degree angle that that meets the outer edge of the cloth belt
Looks like your ab/cod needs to come up quite a way, the lines do not need to match up.
Reference gallery is always a great place to check when you are building
You could trim your smaller ab plate a little more, also don't make the button paint too big. Appears you may also have trimmed too much from the larger plate.
Bin looks great.
Just on your helmet make sure you don't have any excess paint from the teeth on to the gums, looks like there may be a little bit there.
Most of the time it is layers of paint not drying before others are applied or too thick coats, temperature, humidity, to dry a coat can give a very sandy orange peel look and also what type of paint you use. I painted mine with automotive acrylic as it has thin coats, dries quickly between and is a lot harder than a lot of enamels.
I use a generic paint stripper from the local hardware, brush on, leave to interact and then it's a case of using some gun cleaner/thinners and a pain brush for those little hard to get places.
You will need to wash it down with soapy water afterwards to make sure no residue remains.
Can you post up some pics.
Hello and welcome aboard, research is the key to this hobby, some great info in the Getting Started section, would always recommend purchasing form a vetted seller
Adding some foam to the inside of the armor, on the outer of the leg will help bring the thigh a little straighter. Really depends how it fits on your thigh too if you have a lot of room in there they will float so either some foam or even trimming a V section out of the rear could help.
You may find this useful https://electronics.stackexchange.com/questions/382584/running-12v-pc-fan-with-9v-battery
And https://www.quora.com/How-many-9V-batteries-are-needed-to-run-a-12V-fan