Primary Zelda Hacking

I haven't found any tutorials on how to give or take a certain rupee amount from Link in a ZOSE script.  I have a few questions.
1.  What is a command in ZOSE that recognizes a certain tile that Link is standing on?  Say, if I wanted a script to stop and wait for Link to stand on the tile at (X = 5) (Y = 3), how would I program this in ZOSE?
2.  When Link stands on this tile (when the script continues), I want the game to subtract 50 rupees from his wallet.  What would I enter into ZOSE for this?

Thanks for your help.

The memory address CC99 is the YX  coordinates that Link is currently at so by performing a checkmemory CC99 35 the script should wait until Link is at that location.
As for the second question I do not know of a memory address that will subtract some amount X from the rupee total. The addresses C6AD and C6AE are the total rupees the player has so you could change it to a set amount, but that isn't very useful.

Well, it turns out there's no magic address that lets you take away X rupees from the player. I mean, there's an assembly procedure that takes them away, but it's part of the shopkeeper's interaction assembly. The only way you'd be able to do it is to write your own interaction and assembly, which would be quite the pain unfortunately. If you're interested, the code where the game takes away rupees based on what item you're buying is at 09:440A.

Oh well; I just did something else instead.  At least I finally know how to check when Link is standing on a certain tile.  That was bugging me.
I have two other off-topic questions that seemed to me to be too little to put in a separate topic.

1.  Do you know what the sound effect ID number is that's played when a puff is created?  That sound that sounds like something is vanishing?
2.  Is it possible to create a puff outside of the interaction's coordinates (at another tile location)?  What would that look like in ZOSE?

1. http://zeldahacking.net/forum/index.php?topic=153.0

2. Setposition xx yy
    createpuff

Thanks.  I actually looked in the sound effect list and couldn't find it.  I thought you might know.
I'll check again anyway.

Ah, sorry. Hmm... Maybe it's below 4D. I checked the list and I can't find anything. Odd.

Yeah, me neither.  I'll just use the puffs.

My hack is getting off to a great start :)  Thanks guys!