Somehow managed to get enough spare change to get Terraria, so now I get to join the epic wormslaying/building/exploring/everything-ing.

Due to the recent update, I am now the proud owner of nearly an entire treasure chest full of bottles.

Yay!...?

Also, I had to find out online about the Alchemy Station. No indication whatsoever on how to make one. Much like the floating island.

Speaking of, there's only one island per world, right?

Multiple, at least one though

The amount varies with the map size. Also large worlds pretty much require rocket boots and mana boosting items to find them with the height limit there is.

Set (place) a bottle on a table.

Not terribly intuitive, but there you go. You can also place some other items on tables, like potions, or blue candles...

I think you can set them on wooden platforms too. It's handy, because you need an alchemy station to make greater health potions, which are two lesser potions and a glowing mushroom from glowing mushroom-land.

I have seen as many as 3 floating islands a map.

Bigger maps naturally, have more of them. They are of course, also bigger, which is more of a downside than it's worth most of the time.

My only issue with this game is that it won't keep my position when I quit and then I go back to my spawn where I destroy whatever I built there, which forced a modification on my house in order to prevent that (I have the screenshot on my Steam profile but I'm too lazy to post it). Or at least some actual way to pause so that way if something interrupts you aren't forced to go back to spawn and/or hope you don't die.

You have to build a bed to change your spawn point.

If you make a bed (requires silk and wood I think) you can set your spawn point to wherever your bed is.

And I play windowed, whenever I click a different window from the game it automatically pauses for me. (Not saying I like this part though, I'd much rather have a manual pause and let time pass while I read comics or something...)