Soma

You use wire("page")
If rendering a repeater field from another page, let's say
echo $pages->get(1001)->render("repeater_field"); So in template/fields/repeater_field.php
echo "<p>Page containing the repeater: " . $page->title . " " . $page->id . "</p>"; echo "<p>Page currently requested: " . wire("page")->title . " " . wire("page")->id . "</p>"; // render each repeater echo $value->each("<section><h2>{title}</h2>{body}</section>");  

It says 500. https://github.com/ryancramerdesign/ProcessWire/blob/master/wire/core/Selectors.php#L24

Repeaters are located in /admin so access protected too. So I guess for a not logged in user you wouldn't be able to $pages->find(selector)  the repeater pages. I think then you'd need a "check_access=0" or a "include=all".
Since they're in /admin you could also consider implicit "has_parent=RepeaterParentID" or "has_parent=2" ($config->adminRootPageID) instead of exluding trash somehow.

Are they active for the alternate languages even?

PW doesn't allow for multidimensional post arrays. https://processwire.com/talk/topic/691-wireinput-only-allows-one-dimensional-arrays-why/

PW aborts the page in a case the page isn't viewable or not found and renders the 404 instead. A 404 is never a redirect to the 404 page. A 404 always stays at the requested URL and sends a 404 header instead. The rendering of the 404 page does a $page->render(), thus calling the init.php again.
That's why you should include() a functions php with required_once() or alike to avoid redeclarations.

The module core -> PageRender does have a button.

Those tools don't support multi language.

$child->image->url If this only does give you the path to the folder, your image field is multiple and not a single image field.
If you change your field to only allow 1 image, then this would give you the full url to the image.

Usually it works if you just set the "$entryPage->titel" to the value, but think it only works with the ID.
Depends if you use the "ID" or the additional "value" options (id=value|title)
If using value:
foreach ($options as $option) {     $field->addOption($option->value, $option->title); } foreach ($entryPage->titel as $value) {     $valArray[] = $value->value; // array of values selected, not key=>title } $field->attr("value", $valArray); Using ID
foreach ($options as $option) {     $field->addOption($option->id, $option->title); } $field->attr("value", $entryPage->titel); // just passing the field (only when outputformatting off) If that doesn't work just make an array using id.
foreach ($entryPage->titel as $value) {     $valArray[] = $value->id;  }

Make sure your post url ends with a slash.

https://github.com/ryancramerdesign/ProcessWire/issues/779

Or little more efficent
if(!$pages->count("parent=$page, my_field=0")) {      echo "Sold out"; }

Or use new $sanitizer->pageNameTranslate(str)

I'm not sure I understand.
It doesn't work like this. The name on the domain page remains the same for each language. Otherwise it doesn't match what you entered in the module settings.
Language through language segment is set on root "/" page name. It then becomes domain.com/en/ or whatever you set it.

What url does it output?
It may your file field is multiple, then AnimalSound would be an WireArray.

You seem to have a $page->template = 'something' in your template.

Try this
$anzeige->save(array("quiet" => true, "uncacheAll" => false)); Any page save clears some cache. I don't know but it was always like this that when you have page saves on front-end templates happening.
That might interferer with some methods that are cached previously. Not sure why prev and next are affected here, could be a bug or a side effect of an optimization for these methods that have some overhead.
You can also call a $pages->uncacheAll(); before your $page->next and it won't work.

Then your
<h1><?php echo $page->title; "Holiday Cottages"; if($page->editable()) echo "<p><a href='$page->editURL'>Edit</a></p>"; ?></h1> also outputs title of cottage and edit link?
It's like you overwrite $page somewhere (header.inc?) or just the template like $page->template = "something" instead of $page->template == "cottage" ...
Strange, and I don't see what's wrong. Only thing I know is that you're viewing a page that template doesn't have pagination enabled.

I think since you can't unpublish users, Users find will find all anyway.
$users->find("your selector here", $options = array("findAll" => false));

If you watch console it says: 
Refused to display 'http://processwire.com/' in a frame because it set 'X-Frame-Options' to 'SAMEORIGIN'.
Just confirming that it's htaccess.

"/site/assets/files/1015/" I guess you have multiple image field which would be an array. How about 
<img src="<?php echo $page->promote->first->url; ?>" />

But that's not creating a new page, but changing an already created page. As I remember it was always like this.

Or better named
$pagefile = $event->arguments("pagefile"); $id = $event->arguments("id"); $n = $event->arguments("n");

I'm not sure I understand it correctly. But what if you set
'max_levels' => 3, 'collapsed' => true, collapsed means it only shows the current branches.