Accessing data by using own instance of OSM API 0.6

Hello all,
For developing purposes I've started to set up my own OSM infrastructure. The first step was, to install the overall OSM-Website. The github page states that the rails port includes the website itself (including the web front-end, user management, diary functions...), the editors, GPX Uploader and the XML based API 0.6.
For this question I want to concentrate on the OSM XML API 0.6 (more questions will pop up later on but to keep it as simple as possible, I will ask different type of questions in separate threads).

So...I've set up the osm website and I've also followed the Configuration Steps. Now I've tested the website. I can browse the web frontend (it seems everything is working) and user management also works. Next step was to test the API.

I've created some fist requests using a REST-Console and made the following queries:
Creating a changeset using the following URL:

localhost:3000/api/0.6/changeset/create

And the following input using PUT:
<osm>
<changeset>
<tag k="created_by" v="JOSM 1.61"/>
<tag k="comment" v="Just a comment"/>
</changeset>
</osm>

This gives me a reasonable output of showing me a number. For example

4

So...I would assume that this is working, right?

I've made another request by using GET with:

192.168.178.66:3000/api/capabilities

This gives me the following response:

<?xml version="1.0" encoding="UTF-8"?>
<osm version="0.6" generator="OpenStreetMap server" copyright="OpenStreetMap and contributors" attribution="http://www.openstreetmap.org/copyright" license="http://opendatacommons.org/licenses/odbl/1-0/">
<api>
<version minimum="0.6" maximum="0.6"/>
<area maximum="0.25"/>
<tracepoints per_page="5000"/>
<waynodes maximum="2000"/>
<changesets maximum_elements="50000"/>
<timeout seconds="300"/>
<status database="online" api="online" gpx="online"/>
</api>
</osm>

Looks like that this is also working.

Now I want to get some data using the API, so I've tested this by using the following GET request, but there is nothing as a output. But actually this should give me the same output than using the openstreetmao.org link below, shouldn't it?

localhost:3000/api/0.6/node/271428118
http://www.openstreetmap.org/api/0.6/node/271428118

I've also tested it with a request using a bounding box, which offers, using the openstreetmap.org website a map.osm file download. Using my localhost instance, I get nothing. The site/connection is not available.

So...for this part I have the question of how to get data using my own openstreetmap instance including the API. Hopefully I haven't missed anything.

Thanks for your help!