Questions are gooooood, it means you're interested
1) Depends how bad it is, do you want us to have a look at it and let you know?
2) I should have a open face one here you can try on for size
3) You can join SDMA (and for those who haven't, CAMS as well) on the day, just put that on the form where it says member number, just say "new member, will pay on Sunday"
4) Easiest way to enter is to right click the entry download link, save the file, edit with your details - you are the entrant (owner) and driver so need to fill same details in both sections - in the CAMS licence section I would say you have the 30 day slip but no number yet - pay the $70 into the SDMA bank account listed and copy/paste the receipt details into an email and attach the entry form and send to the email address listed on the form (BEFORE 8pm Wednesday to get the saving).
5) I would call CAMS and ask them to fax a confirmation to you that they have received your application as a backup
6) and last but not least - No special screws required
I think you will enjoy this, it doesn't have the wear and tear of circuit racing, but has the time trials fun of trying to beat your previous time. The club is also very supportive.
I'll PM my mobile number and if you want to swing by, give me a yell.