[Q] A few questions (mainly bootloader) topic

Hey there everyone!
Let me apologize in advance if these questions have been answered before but I'm so confused right now and I don't want to brick my new Xperia Play.
I had one a year ago but my little cousin trashed it. I finally got a new one today and want to venture into the custom rom world.
The one I bought is an R800a from ebay.
I used to have an R800i, which I just unlocked with the original sony website.
Now a few things that confuse me:

1.
I want to unlock the bootloader, so I looked for the Rooting Status in the *#*#7378423#*#* but noticed that it was completely missing. Is this normal? Or does this mean that my bootloader is already unlocked?
If it's of importance, I can use my German T-Mobile Sim card without a problem.
Is there a way to check if my bootloader has been unlocked already?

2.
I've read about the test point method of unlocking the bootloader. Does this work on devices where the menu point Rooting Status is completely missing?

3.
I want to use it for gaming, are there any recommendations you can make for custom roms for a 800a?
I'm leaning towards the true ancestors 4.0.4.

Thanks in advance for your help! I'll try to provide any info you need.