ACHDS Exam
I have done my ACHDS and am now taking my ACDT and ACTC next week.
I would say you have a good chance at passing if you can handle the day to day stuff. You have to make sure you have a decent handle on Open Directory (also for the ACTC as well), which I am not terribly good at!
Regarding Apple based employment - I have found a lot of positions open recently, you just have to know where to look!
Try going to online agencies, such as reed.co.uk, there are quite a few positions there...
Good Luck!