I've been told there aren't any networks around anymore that this phone supports, but I don't know for sure. You can expand the network section on GSM Arena to see what it could connect to.
XPlaystation does strip out the phone stuff, or at least the apps. It might still have support for a phone app built in. I haven't used a Play as an actual phone in several years.
Well as I said my solution for it was changing my ROM to one with a newer Android version
But I just googled a bit and found this on the Sony forums:
"download and install this apk, https://www.apkmirror.com/apk/google-inc/google-play-store/google-play-store-5-0-31-3-release/google... to your Xperia Play and install. The Xperia Play supports apks made for android 2.3 and under, and that is the version that supports the apk, afterwards reboot your phone, then clear the data for the Play Store. Then the Play Store will work if you are signed in, of you aren't just sign in reguarly. I fixed my Xperia Play R800X and R800I with this method"
Haven't tried it personally but sounds like it'll work
I've actually been thinking about working on a custom sliding case, but I've never messed with 3D printing before. I think it would actually be pretty simple to get a bluetooth controller with sliding analog sticks and the base, gut it, and reformat it into a better case. Maybe event the 8BitDo Lite?
Check that you have a libminecraftpe.so in /data/data/com.mojang.minecraftpe/lib/. You should be able to find it inside the APK in the armeabi-v7a folder. The app might need to be installed to internal memory, too.
A lot of the copies of MCPE floating around out there have been hacked or modded in some way. I found a collection of old versions that seem untouched here, but I haven't tested all of them.
I just got that PM and yes, it will work... mostly.
Something about the R800x kernel will prevent charging through the USB port when running on an R800i (I used to have an R800i which exhibited this issue and another person that tried my ROM on an R800i had the same issue as well), which is kind of a big deal unless you have something like a battery charging cradle:
https://www.amazon.com/Sony-Ericsson-Battery-Charging-Cradle/dp/B003F8L8M8
Unfortunately, it's basically R800x only if you want full functionality.
Because of your lack of windows, I'm not sure if there is a way to just root, but there should be indeed. You could always go with a virtual machine like I said. Maybe have a look there?
http://forum.xda-developers.com/showthread.php?t=1312859
As for the N64 and ICS, the touchpads are indeed only working in ICS on N64oid, but not with mupen. The problem is that although the touchpad works, they also generate lag and the O button functions as a back button no matter what you map it to, so it's a bit annoying. I personally prefer to use this app instead and stay on GB:
https://play.google.com/store/apps/details?id=com.locnet.gktouch&hl=en
that lets you map the touchpads to areas of the screen, and so it bridges the gap.