No, You are unable to buy Windows 10 (Bedrock Edition) and get Java Edition for free.

However, if you bought Java Edition before October 19th 2018, you are able to redeem a free copy of Bedrock Edition on https://mojang.com/.

Following link details further. https://help.mojang.com/customer/en/portal/articles/2064007-minecraft-for-windows-10

Sadly the XBox360 Version of Minecraft was a standalone title not compatible with any other Version of the game.

To explain the Version stuff: There is no "upgrading" to bedrock. Minecraft in essence is a name given to 3 seperate games:

• the original Java Edition of the game which is only available on PC

• Bedrock Edition a completely different code written in C++ which is performance optimized for the in general weaker Mobile phones (This is the Edition that comes to all Mobile Devices, most modern consoles). This Version is as far as I know the same as the Windows 10 edition [here originated most of the confusion between bedrock and Java]

• each earlier console (XBox 360, PS3 and Wii) had a Version on its own and neither of them was cross-plattform compatible

Unless you are playing the SAME EDITION you cannot play together with others. Meaning you should be able to play with the PS4 community with your mobile phone or tablet, since both devices mainly operate on the bedrock edition.

I am quite sure that this list is not complete, so please enlighten me so I can update.

Also check out this question.