ManaCube supports versions from 1.8 to 1.20. Depending on your version, you may find that some blocks are textured differently or that you may be unable to do certain tasks whilst on some servers.
When you log onto Manacube, you'll join the legacy-hub. You can click on the compass to open a server menu. Currently with 1.8, you can ONLY join Parkour and KitPvP.
If your punishment is over 24 hours (Not equal to 24 hours), you are able to file a mute/ban appeal. You can refer to the appeal article if you need to read over the requirements you need when writing an appeal. If your appeal is rejected, you'll either need to wait out the duration of your punishment or wait a specific time before you're allowed to appeal again. You are not able to buy an unmute or unban.
Yes you can play on your phone assuming you have Bedrock Edition.