Euphy

trunk/db/item_stack.txt

This is disabled by default.
set .ShowID,0; // Show item IDs? (1: yes / 0: no) There's no way to increase the size of the message window.

Read: Basic_Scripting#Conditions.2C_Variables.2C_and_Set
You're using an account-based variable instead of a character-based one.

trunk/npc/re/merchants/ticket_refiner.txt
(disabled by default; you have to enable it manually)

Add/change this in the "Keeper" function:
   if (getarg(0) == 4) set .@j,1;    for(set .@i,1+.@j; .@i<9; set .@i,.@i+1)         set .@menu$, .@menu$+"Arena "+.@i+" ["+getmapusers("pvp_n_"+.@i+"-"+getarg(0))+"/20]:";     set .@i, select(.@menu$)+.@j;

trunk/npc/merchants/refine.txt

trunk/npc/guild/agit_controller.txt
trunk/npc/guild2/agit_start_se.txt

I'm fairly sure this is all done client-side through the item name tables. I can only think of adding custom cards and using the card prefix tables, but you'd be down a slot on all equipment.

It doesn't.
1736,ALIOT,Aliot,Aliot,112,15669,1,2448,1836,2,608,697,106,15,111,56,55,42,62,75,10,12,1,6,60,0x318D,200,1296,432,360,0,0,0,0,0,0,0,7512,2000,7507,3000,2516,10,6214,200,1810,10,985,10,13405,15,0,0,0,0,4402,1If it does, it's not related to the official (unmodified) files.

Read: Make items drop identified?

Our Core Developers are looking to do a better implementation of this, but it's pretty far back on our to-do list.

Added support for costumes and robes in v1.6a @ r17366.
trunk/npc/custom/quests/quest_shop.txt

CREATE TABLE IF NOT EXISTS `login` ( ...
`sex` enum('M','F','S') NOT NULL default 'M',

It's an OnTouch NPC (likely invisible), not a cell type.
Read: OnTouch

trunk/npc/custom/healer.txt
http://rathena.org/board/topic/81860-r17280-slight-script-engine-update/

if (getequipcardcnt(EQI_HEAD_TOP)) { successremovecards EQI_HEAD_TOP;
dispbottom "Cards are not allowed on this item.";
}

Great question! I added it yesterday. ^^
trunk/npc/re/merchants/ticket_refiner.txt
You should update to r17338 to get the full database entries as well.

bonus bVit, not bonus2 bVit.

A non-atcommand alternative is:
percentheal -100,0;

if (getequipcardid(EQI_HEAD_MID,0) != 4198) { mes "A Maya Purple Card must be slotted in your middle headgear.";
close;
}

set .@i, countitem(7179); if (.@i) {
delitem 7179,.@i;
set #CASHPOINTS, #CASHPOINTS+.@i;
}

See this topic: Requesting Card Seller Script

This was fixed in r17221, sorry for any inconvenience this may have caused.

It depends on the situation. Some examples...
Scope variables: Arbitrary variables with no meaning, ex. to handle for/while loops or to store random numbers. Anything in an uncommonly-used section of an NPC, where it would serve no purpose to store the data permanently. Scripts where different instances hold different values that should not overwrite each other, ex. storing a player's name in dialogue or other player data. NPC Variables (OnInit): Commonly-referenced variables in a prominent NPC, ex. basic configuration settings in my Quest Shop or WOE Controller. Large, occasionally-referenced arrays or simulated multi-dimensional arrays (setd/getd), where it would be a waste of processing to re-set the values each time the script is called. Stored values in NPCs with many duplicates, since NPC variables are only stored for the main NPC and not its duplicates (i.e. this saves both RAM and processing). NPC Variables (not OnInit): Variable that will be referenced later, after the current script terminates, ex. counts in event scripts. Temporary reference needed in another section of a script where scope variables are not passed (goto/donpcevent), where the variable is generally un-set (to zero or "") after use.  (This is very uncommon; I may actually be the only scripter that does this.)