Terraria – How Long Do Dropped Items Persist?

The liquid physics in Terraria are not completely precise. You can abuse it to duplicate them. Good thing, too, since transporting a decent amount of lava/water anywhere is a huge pain.

1. Infinite container: If you make a liquid container large enough, the amount that drains each frame is rounded down to nothing, for some reason. For example, a 49×25 liquid container with a 1 block hole will create an infinite amount of liquid (video example of this). This will break if liquids are settled (via the server console or when saving and loading the map).
2. Liquid splitting: When a liquid falls onto a single block and could flow down both the left and right edge, it will. Somehow, this leaves you with more liquid in total than you started with.
3. Bucket weirdness: Buckets create 1 block of liquid when they're emptied, but filling them seems to require less. If you place a block, let some of it flow and then quickly pick it up again, you will have a full bucket, but some of the liquid will remain.

Applying #2 and #3, this is a very simple liquid duping setup:

The lava is placed on the edge, where it flows into both the container and the 1-block "basin" on the right side. Both "portions" are enough to be picked up by a bucket again (though in this case, the first scoop will be spread too thinly in the container).

All of the comments you've received pretty much collectively give you the answer.

All of those enemies do spawn in 1.1.2; they're very rare, though, and require the right conditions/ biome to spawn. Water candles and battle potions will increase their spawn rate, but at the end of the day a lot of it is luck.

The groom spawns on the surface during blood moons, and Tim spawns at random underground (stone layer). Doctor Bones spawns in the surface or underground jungle at night, and more commonly during a blood moon.

So all you can really do is wander around, take advantage of the blood moons and of battle potions/ water candles, and hope for the best! You'll encounter them eventually if you keep at it.