A few questions that I haven't found answers to in a looong time?

All the stuff you listed is for when you get the freeman rank and can enter the portals to the factions world . (Portal of emeralds at spawn)

 

On top of what king said,
TNT is used to blow up bases to grab there stuff in the free world where you make factions.
Obsidian is used to make a base and/or auction it for money (what I advise doing if you are not new)
And creeper eggs which you should auction by doing /auc once you are A-Prisoner. You can also use them to blow up chests in the free world!

 

Im rank d and have 200k y wont it let me go to prisoner a????

 

Have you tried clicking the C-Prisonor rank at warp rankup first?

 

You have to go up each rank first (d, c, b, a ) You can't just skip through all the ranks.

 

Also, you'll need a lot more than 200k to go through all the ranks, I'd recommend going down to the mines for a while.