Hi Andre, I can help a little....
1. AD users are not imported...when a user logs into the client portal, their user account along with all their registered SMTP email addresses will be populated inside the DB. Can can see these in the Staff portal, under the users module.
2. I've not tested this, however, if you have a w2k3 AD domain, and you've set your loginshare account to authenticate against an account in a root domain, users within child domains should be able to login as long as you're not restricting the transient trusts. Again, I've not tested it....will give it a go
3. Yes.
4. No simple way....you'll have to write an import script and run it at scheduled times. We have done this here, however you need to bear in mind a few factors; (a) you'll need to specify the exact OU objects you want to import and verify that they are actually user accounts and not servers etc, (b) you'll need to create further MySQL tables to take account of user account changes, i.e. names changes following marriages etc - using the AD 'objectguid' is a good way to do this, as that item is unique throughout the life of an AD account, (c) you'll need to amend/delete/append new SMTP email addresses of users as SupportSuite does not take into account this when an AD user logs in....and everything in SupportSuite is tied to an SMTP account (i.e. a user leaves and a new user starts with the same name....that'll cause you all sorts of issues - if you have 10,000+ users like us you're likely to to experience this.
5.
http://manual.kayako.net. It's still work in progress.
Mark