Hi Team,
Thanks for your kind help and please pardon me in case this question is already answered. I'm unable to find this information on the forum or internet and hence need your inputs as it is really important for me to plan my next steps. 

Background Info:
My wife got a job offer in Germany. Me and my wife applied together for Germany visa. My wife applied for work visa (Blue Card) and I applied for Family reunion visa. Both our visa is now approved (and stamped on our passports). In her visa it is mentioned Blue Karet EU, Type: D, Duration of stay:XX. I applied for family reunion visa along with my wife and got the same along with her. My visa is family reunion (Type: D, 90 Days of stay). We are planning to move to Germany in August

Questions:
1. Is my wife's blue card visa already approved as it is mentioned on her Visa 'Blue Karet EU'? Or is it just a recommendation and it will be decided once we reach Germany and complete the procedures. How much time does it take in Germany to actually get the Blue card visa post submiting the application once we reach Germany?
2. I am interviewing (online) for few companies in Germany. Will I be allowed to work in Germany once I reach there (as I've got Family reunion visa)? Or do I need to wait for say 3-6 months till my wife actually receives the Blue card visa post completing the formalities (I've heard it takes lot of time to actually get the Blue card visa post reaching Germany). So can I start working on the day I reach Germany on Family reunion visa if I can get a offer/contract from company in Germany? 
3. What does 90 days on my stamp means? i need to enter Germany in 90 days? 

Thanks once again for your kind help. Please do inform me in case you'd need any additional details.