Symptoms: Report looks OK in the browser, but export to CSV gives problems with exotic characters.

Fix:

Set [Shared Components -> Application -> Definition -> Globalization ->] Automatic CSV Encoding to No.

Now when I run page 8 in your application and I download to CSV, it is properly encoded in UTF-8. Of course, when my version of Excel opens it up directly, the characters appear corrupted again because my version of Excel expects windows-1252 encoding. However, if I import the data in Excel (Data -> From Text), and I choose File Origin of 65001: Unicode (UTF-8), all of the data appears correct."


Source: http://forums.oracle.com/forums/thread.jspa?messageID=9308830&#9308830

You can hide columns by putting a condition on them of type PL/SQL Expression and using the following as the expression:
NVL(:REQUEST,'EMPTY') not in ('CSV','XLS','PDF','HTMLD','RTF') That will check the APEX bind variable "REQUEST", and if it is CSV, XLS, PDF, HTMLD or RTF then the column will not be shown.
Note that newer Apex versions also have an "Include In Export / Print" option, which might be sufficient for most purposes.

To stop a column from showing up for an email, you can use the following:
NVL(wwv_flow.g_widget_action, 'EMPTY') != 'SEND_EMAIL'
Source: http://stackoverflow.com/questions/9700660/apex-interactive-report-hide-column-in-csv-download
Note: This source suggests using XML as one of the :REQUEST options. That is incorrect, this should be HTMLD as in the example above.

A simple way to remove the rather ugly "Download" link from the bottom of Classic Reports, and replace it with a nice button.
The button triggers a Dynamic Action that clicks on the original "Download" link (whose text is hidden by some css).
See the Code section below for details. Note you need a Static ID for the report region.

Note:
In older Apex versions and/or browsers the querySelector used to be different;
I assume the Apex html flow has changed since then, so if you have problems you may want to try the old version below.
Thanks to Ajay for pointing this out!
document.querySelector('#p1007-classic-report > div > div.t-Report-links').click();

Page

Name
	Page ID	1007
	Name	Apex - Reports - Download

Region

Identification
	Sequence	40
	Title	Classic Report - Download Button
	Type	Report
Source
	Source Type	SQL_QUERY
	Table Name	EMP
Attributes
	Static ID	p1007-classic-report
	Region Display Selector	Yes
	CSV Export Enabled	Yes
	Link Text	<div style="display: none;">Download</div>

Button

Name
	Button Name	P1007_DOWNLOAD_CSV
	Text Label / Alt	Download CSV
Displayed
	Sequence	10
	Display in Region	Classic Report - Download Button
Action When Button Clicked
	Action	Defined by Dynamic Action
	Execute Validations	No

Dynamic Action

Identification
	Name	download csv
Execution Options
	Sequence	10
When
	Event	Click
	Selection Type	Button
	Button	P1007_DOWNLOAD_CSV
Advanced
	Event Scope	Static
True Action
Identification
	Action	Execute JavaScript Code
Settings
	Code	document.querySelector('#p1007-classic-report div.t-Report-links a').click();
Execution Options
	Sequence	10
	Fire On Initialization	No