I have limited knowledge of Minecraft except for the tons of builds I've had to look at and Stampy/Dan TDM videos I've had to listen to over the years (I have an 8 year old son). He has always played Minecraft PE and on XBOX, and has asked over an over to get the PC because of all the mods that he can't do on PE. So for Christmas I decided to get the Minecraft that came on my computer working but it said I could buy the full version and sent me to Microsoft. I bought him the Minecraft for Windows 10 Master Collection. It came with skins and texture packs etc. I never thought that there were different PC versions of Minecraft and when he went to play, the things he was trying to do wouldn't work. He tells me that he needs the Java version. From all I've read it looks like I am out of luck and just have to eat the cost of the W10 version and now I have to buy the Java version. So these are my questions:
1) Since the W10 and Java versions are different, can I have both on the same computer in case he also wants to use the W10 version?
2) Can he use the 1000 minecoins, skins and texture packs that came in the W10 bundle in the Java game?
What you buy is an account. The stuff that came with your Win10 MC purchase belongs to that account, and can only be used there.
When you buy Java MC (via minecraft.net) you also get an account. It is unrelated to Win10 MC account.
Good news is, practically any extras with Java MC are easily found for free. Tons of skins, texture packs, mods - you just download them off hosting sites (exercize caution - some sites are malware heavy) and drop into a proper folder.