Yes, of course you can use Errai without Maven and use Ant instead, but we don't provide quickstarts for it. What are the problems you are having? You can also join us on IRC (#errai on freenode). We can help you setting things up there.
you could provide a list of the exact dependency hierarchy for each of the modules (e.g. which jars do I need if I only want to use the marshalling feature). That would be very helpful for people who do not work with Maven.
Yes, we had planned to do that for a while now. In fact just recently a JIRA was created for this by another community member: https://issues.jboss.org/browse/ERRAI-328
You can use it to track the progress. We'll try to do as soon as possible.