The w39 is all stainless steel. 

I owned many watches and still do, these are just the ones that i found to be perfect to me. If i end up not liking one i just sell it again. 

What i look for in a watch is something rare but not so rare that no parts are available. It has to be special but not immediately look like it is, if no one cares about the special thing it’s even better. And of course it can’t be too expensive.
 

I owned a few mechanical watches and in my opinion if you seen one you seen them all. Sure a rolex is a nice looking watch with great history but ones you get past that it’s just another watch except you paid a lot for a watch that isn’t all that practical and doesn’t even keep good time and I’m confident I’ll get there in matter of days. Quartz watches are just way more interesting to me.

Well, all this can be had for less than a hamilton khaki, a watch that most see as an entry level watch. You just have to be more patient for good ones to pop up on ebay. 

the c801 is part of Casio’s first calculator watch line. It was meant to compete with seiko and citizen calculator watches that required a stylus for input. The larger buttons could be operated with your fingers. The buttons on the right serve calculator and stopwatch functions. the ca 53w has one extra row of buttons on the front for that. The buttons on the left are light, time setting, date display and mode selector. 

quartz movements do not need servicing unless it's out of spec or broken. A mechanical movement needs servicing because its components are under tension, have fast moving components and heavily rely on oils and friction to keep time. Most quartz watches have none of these issues and it's probably more harmful to take them apart on a regular bases. What usually makes a quartz watch fail is a case that's not properly sealed or damage from improper battery changes. A well taken care of quality quartz will last a lifetime and beyond. 

gw5000u is a current model and is not rare on every market, it's readily available in europe and japan at least. It's also not really a homage, in that sense every square is an homage, i think you confuse this with a limited edition anniversary square gshock that casio does every 5 years. What makes it more expensive is the premium built and it's made in the japan gshock factory where all premium gshocks are made

GW-M5610-1 is a square with atomic clock (GW-M5610U-1 is the latest updated model)

GW-B5600MG-1 is like the above but with additional bluetooth time sync (unnecessary if you have good atomic clock reception)

GW-5000U-1  is a premium version of the GW-M5610U-1 with the exact same module, this adds a stainless steel case under the rubber shell and has a nicer softer strap and is made in japan

I own a both GW-M5610-1 and a GW-5000U-1 and i must say the gw 5000u feels a lot more substantial. Not that the gwm5610 feels cheap in any way, it's still great value for money. The gw5000u is also slightly larger and heavier than the gwm5610 which makes the gwm5610 a bit more comfortable. 

So in my opinion if you have the money to spare go for the gw-5000u, if you're on a tighter budget you're not missing out on anything by getting the gwm5610