He might not need to make that much.. he could raid an abandoned mineshaft for some.

He’ll still need a fair bit for the max beacon, though.

Yes, I’m afraid so. But you have to do it after you’ve earned The End (by exiting The End via the End Exit Portal).

Also, your water’s got electrolytes in it… that’s what plants crave!

The adventure time achievement (visit all biomes) is specific (and there are about 30 including all variations, I think)… And there’s no way I’ve found to see which ones we’ve been to in vanilla (I’ve searched!). That achievement and the series for the wither and beacon are all I’m needing in the game. I can easily get the wither/beacon ones as soon as Spork lets me have some of his hoard of skulls, but the adventure time one vexes me. Every time I hear of someone locating a biome that I haven’t been to, I rush off to visit it, hoping it’ll prove to be the last one. I’ve gone on Chiseled Stone hunting expeditions (overland, not through the nether), I’ve gone after hardened clay, podzol, packed ice, sand, clay, all the saplings… I take meandering routes to visit everything that looks like slightly different terrain on my way to my target. Still no achievement. :/ (And I have Dynmap to help me spot different grass/tree/ground cover!)

Oh, I looked up the On a Rail achievement to understand why you said it had to be a straight line… it doesn’t technically have to be straight, you just have to travel to a distance that is 1000m ‘as the crow flies’ from where you started. So if you have a turn, your rail would have to be longer to account for Pythagoras’ shenanigans.

I was reading some posts on Mojang’s bug reports, and it looks like Adventuring Time may be bugged and as such it is currently unachievable, although I am not 100% sure that’s the case.