Achtung Achtung Achtung

I would strongly suggest that you negotiate a fixed salary of atleast 66000 Euros per annum.
This way the company can apply directly for a permanent residence for highly qualified people for you under Paragraph 19 of the Foreigners Residence Act (Aufenthaltsgesetz)
This way neither you nor your wife would need German and also she can work from the very beginning.Negotiate with them based on this and also that this way they wont have the hassle of workpermits and going through the so called 'priority exam of the labour office' (Vorrangsprüfung von Arbeitsagentur)where they need to prove that no German/European is suitable for this job.
Ask the HR guys to look at this:
For the law
http://bundesrecht.juris.de/aufenthg_2004/__19.html
To understand how you come to the figure of 66000, they need to check _
http://de.wikipedia.org/wiki/Beitragsbemessungsgrenze
For the language exam exemption for your wife:
http://www.chennai.diplo.de/Vertretung/chennai/en/Formulare__RK/Visa/download__visa__InfosheetGermanKnowledgeFZ,property=Daten.pdf
Read paragraph 1
Insist on 66K fixed. Just for your info, bonus doesnt count into it but vacation and christmas money does