I'll do my best to answer your questions
1. Do Widgets support animated gifs? (I ran a first prototype on blackberry 9500 simulator which doesn't animate )
Yes they should work. We have found that with the beta, some simulators/devices display them fine while others do not. We are trying to get to the bottom of the issue.
2. Did someone build a Widget with a maps? Is it possible to view the blackberry map !within! a Widget (like iPhone Apps showing the integrated Google map) or is it only possible to open the map application with invoke() ?
If not , did someone try to run any dynamic map(JavaScript) API in a Widget (like Googles or Yahoos)? Does it work or is it more wise to rely on static maps?
At the moment there is no way to embed BlackBerry maps into your HTML content. I would suggest using Google Static maps as an alternative for an embedded view. As you stated, Invoke is another option
3. As far as I understood, Widgets will run on phones with OS 5.0 Version. Can someone tell me when phones with this OS version will be available on US and on EU market?
The list of existing in-market devices that will receive OS 5.0 has not been published. You can always check out some of the outside blogs to get an idea of rumors of what devices would be receiving this upgrade. 
4. I have issues with the Blackberry simulator. Everytime I override a Widget with a new version, I get a null pointer exception. (JVM Error 104). Is there a work around or do I have to reset the simulator everytime before I upload my widget?
Typically resetting the simulator is your best bet. However, what I do when I am building a widget is load all the content for my widget from a web server I have locally running on my machine. I do this by setting the start page to be the URL of the page on my web server. That way I only ever have to compile a new widget when I make changes in my configuration document. Then when I want to deploy to a real device, I change the location of the start page to be local and re-package my widget.
Re: GIFs, Maps and other Features
Did you add the domain of your start page in the white list <access> element..
For example using your IP:
<access uri="http://123.123.123.123" subdomains="true"/>
Q: Will this continue to be supported when the Widget API comes out of beta? If so, it offers an interesting deployment model whereby all that gets installed on the end user's device is the config.xml and everything else is dynamically downloaded on-the-fly from an app vendor's server. This means you never have users on outdated versions, etc. Very cool indeed
Absolutely this will still be supported. We want to give you the flexibility to put your logic and content wherever you want. If you want it all local, package it in the widget archive. If you want it all remote, then just have your config point to a remote site. You can then also blend what you want local and remote.
It all then becomes up to you on what works best for your application experience for online/offline and load time and network latency.
You can even have remote pages that pull in local images, css and JavaScript files... For example, I could serve up a page from my website that has an image tag in it like this:
<img src="local:///myimages/myimage.png"/>
Or a script tag that looks like this:
<script type="text/javascript" src="local:///myscripts/script.js"></script>
The same would hold true for CSS and other types of content. That way if you have common images/js/css across your application, you can put it all local in the widget, and only serve up the HTML content from the server.
It provides for a pretty flexible architecture.
Hopefully that gives you some more ideas of some cool combinations
