Hey Ian --
So glad to see you back around here!

A good online level test... hmmmm... I suppose the word \"good\" is really subjective.
I have a couple of suggestions:
Wordskills, and
DYSE. The DYSE site asks for a name and an email. What you can do is ask your student to do the test submitting his/her name, but using your email address so you get the results.
The problem with both of these tests is that they are online tests. So if you don't have online access in the classroom (your or their house?) you won't be able to use the test.
I have a list of levels and the general grammar knowledge that should be known and used in these levels. It was a list given to me by a consulting agency that I worked with, so I can't take credit for it. However, I have modified it a little and consolidated some of the information. I have uploaded it here for you to download if you are interested.
I work primarily with adults and have found that the majority of them place in an intermediate/upper intermediate level. Don't know if that helps you at all. I also use a text book in class enriched with authentic materials that I prepare... radio programs, magazine/newspaper clippings etc. I use a pencil and paper level test that I have developed according to the attached level standards outline and the coursebook I use in my classes. If you are interested in knowing more about it, email me.
With regards to first class lesson, how about a \"get to know you session\" where you can assess the student's ability to give information, form questions, etc and establish a rapport. You can assess the vocab knowledge by having them describe their job, their house, their family, their dreams, etc. I have this great little book called
The Book of Questions which presents all sorts of challenging hypothetical situations for people to address. A great resource for practicing the conditionals! I highly recommend it as a \"must buy\" for those who are teaching English.
Hope this info and the websites are helpful!