Minecraft (Xbox 360) item question?

I just recently purchased the Xbox 360 edition of Minecraft, Im curious as to what may have been left out. I spend time on Minecraft Wiki and notice a considerable amount of items I have not come across. I have hit the bottom of the map in several areas and have yet to come across a stronghold or abandoned mine shaft which I hear is a great way to gather rare metals, gems, and resources (diamonds, seeds, redstone, gold, iron, etc.). I have not found any melon or pumpkin seeds amid "Overworld" whether it be at the surface or in caves and ravines while spelunking. I have also located obsidian and have a diamond pick axe and for whatever reason I cannot mine the obsidian. I've been told I could use enchantments to try that but I dont think an Enchantment Table exists in the 360 version yet. I have also read about villagers of which to trade goods with. I have explored a good 60 to 70 percent of the surface of overworld alone as I have explored all the islands I've located and regions of desert, tropical forest, plains, and a snowy forest. Despite all that Im most curious as to where to find pumpkin and melon seeds to expand my farm, how I can locate villagers (I have located 6 uninhabited separate villages but no villagers) and why I cant mine obsidian with the highest quality pickaxe in the game when that's what the helper hints told me I needed to do. Any help or tips is greatly appreciated however I ask that you provide True information. Thank You