1) How to change allowed size from 200kb to more?
2) What to do, that uploader keeps original image name (if in need, then adding only some number to original name)?
3) I used just extention. Did not realy understand does I need to edit some file too. I have "Upload" button when after pressing "reply" or "edit". But not on the standart view. Does I need to edit post.php or another file (I have done only installing extention)?

There are now two upload forms in Post Reply, but I don't see any way around that with the current hooks available.

2. Good idea, I will look in to it.

1. The image post field should be above the previos posts in the topic that you see when you make a new post.
2. When editing a post the image uplod field is missing.

http://fixpc.co.za/download/image_upload.zip

You may see the code of manifest.xml of any official extension as an example. I'd advice to look into pun_bbcode manifest.xml, because it's quite simple.

It seems the basis of the extension system is this manifest.xml file:

<?xml version="1.0" encoding="UTF-8"?>
 
<extension engine="1.0">
  <id>example_extension</id>
  <title>Example Extension</title>
  <version>0.1</version>
  <description>This is a short description of the extension.</description>
  <author>John Doe</author>
  <minversion>1.3 Beta</minversion>
  <maxtestedon>1.3 Beta</maxtestedon>
  <dependencies>
    <dependency>another_extension</dependency>
  </dependencies>
  <note type="install">Add notes before the user installs the extension</note>
 
  <hooks>
    <hook id="vf_start"><![CDATA[
    // Include a file from the extension directory
    require $ext_info['path'].'/foobar.php';
    ]]></hook>
    <hook id="vf_pre_header_load"><![CDATA[
    // Call a function from foobar.php
    foobar_function();
    ]]></hook>
  </hooks>
</extension>

I think I can start working from here but before I do, please let me know if this template will work for PunBB 1.3. If not, what changes should I make?

Read about extensions developing for FluxBB. Extension developing for PunBB is very similar.

Also you can read about hooks here: http://punbb.informer.com/forums/topic/ … are-hooks/