Vangoddy Slate 3-In-1 Hybrid Laptop Bag for 13-14" Laptops & Tablets (VGSlate13GRY)

I will use this for work, where the tablet is used for customer signature. Does tablet move in/out easily? Can folder-sized market materials fit?

What is the small zipper compartment on the back top used for? Might you describe what you put in different compartments?

Does the 12.5" model fit a macbook air 13? air is 12.8" w, bag is 12.75", but air is only 0.7" thick, bag is 1.4". experience?

Can you fit a 15.6" laptop, yellow pad, planner, and 3-ring binder in this thing?