Painting the splash back behind the cooktop is not recommended as it's flammable and will likely peel, blister at least or ignite or release chemical fumes at worst. I love the chalkboard though, although I would mask up a doorway on your wall between the fridge and island and paint that, like a menu board, handy for shopping lists or recipes, and will look clever without being permanent. For the window area, I think those two narrow windows are smart and have personality. You can make a mdf pelmet for above them, simple as. Measure the width of the window frame, and cut about 150mm for each side. Ou can have the timber yard cut the mdf into a 200mm strip, and you simply cut the lengths, 1 x front measurement, 2 x side measurements (150mm). Say. Screw sides through front board and cover with wadding also know as Dacron from fabric store, about $10.00 worth, secure with staple gun and repeat with a fabric of your choice. This is where it's fun, I think something like a lemon lime print or citrus stripe, and perhaps make the top of those pellets have a mdf top also so you can place mason jars filled with lemons or limes on them like a ledge, it will look like fresh preserves in a kitchen window and the blackboard wall will tie that into a theme. Like the roman blinds too because fabric will add colour and style cheaply. Don't mind you took off the doors because you are neat, and items seem to match but that can become messy quickly. Reconsider the blackboard behind your cooktop for safety, and even could go to a tile supplier, buy a heap of se nods or discontinued tiles in your mustards, yellows and teals, break them up and mosaic a sheet of fibre cement sheet cut to fit. Then you could attach that to the wall directly over the old tiles, and it would be made by you, the right colours and have that bespoke eclectic look in a cooks kitchen. Sometimes it's as simple as grouping things like a timber chopping board leaning up the wall,a bowl of picked lemons with leaves on, and a teal striped washcloth for it to have those zingy pops of colour.

I agree that the floor is the problem. If you are short of cash, think about what your final aim is (a five-year plan?) and work towards that. Changing the cupboards and splash back are not going to have a big impact, as what you have is quite a classic look, but the floor is very ugly and outdated. No matter what you do or how much you spend, your kitchen will be dominated by the floor until you change it. Timber would be great because it would add softness, warmth and texture to the space, but obviously it depends on what other flooring you have and what your long-term plans are. Perhaps subway tiles would work as a splash back. To my eye glass would just look out of place with the style you have, plus it is expensive. You can buy lovely subway tiles very cheaply.

It can be done. Clean any grease etc off the doors using sugar soap, fill any holes/deep scratches with polyfilla, reglue any loose edge strips. Sand to remove any shine, use a fine/medium grit sandpaper & be careful not to sand too much around the edges. Apply 1st undercoat (I used oil based sealer binder), leave to dry for 24hrs then lightly sand with black very fine sandpaper, apply 2nd undercoat. Leave to dry & cure for at least 24hrs, sand again. Apply first top coat (I used enamel paint, gloss). Would not recommend using high gloss paint as it will exaggerate any defects. Leave to dry for 24hrs, sand lightly with fine black sandpaper. Apply 2nd top coat then leave to dry for at least a week before using. Recommend removing the doors & taking off all hardware, also paint the backs of door. Put a long screw in the handle hole or catch hole so you can manoeuvre the door(s) while painting. You can do the undercoats outside but recommend doing top coats in a dust free area inside. Wear disposable rubber gloves for easy cleanup. You can speed up the process by using water based undercoats & topcoats but it won't be as resilient. Below is a laminate bathroom cabinet before & after painting.

Perhaps light grey overhead and Japan black lower. How high are your ceilings? Inspiration shots below. I agree 2700 would be too high in black but 2400 would be fine.