Hi Mar!
Congrats to your loss!

As for Induction, I think Dr. Atkins said you can stay up to 6 months at least, if you feel like it. However, there is an issue of getting "oversensitive" to carbs for some people, meaning if they stay on too low an intake for too long, any raise in carbs might cause weightgain. So, for the sake of weaning your metabolism, maybe try some kind of OWL "rungs" after a while.

I stayed on Induction carb levels (17-23g carbs) for about 3 months, but gradually introduced more OWL-type foods. As for nuts etc, it seems to be highly individual how they effect your weightloss. Some people stall (or experience a weightloss slowdown) on nuts, some don't. Some people stall on cheese, some don't. Etc. You get the picture. So, whenever you're ready to introduce new foodles into your menue, take one a week (the way OWL is prescribed in DANDR or at the atkins.com site) so that you will be able to monitor if that particular food has any negative effects on your weightloss or not. If you add more in at a time, it will be harder to evaluate what caused any (potential) problem.

Best of luck!