A: Hopefully, you already received you green card by now. If not, don't worry. USCIS works in mysterious ways. There is no way to predict why some dependents are approved before primary applicants and vice versa. Keep checking in periodically. Unless USCIS has a reason to delay your application (criminal conviction, grounds for inadmissibility), you should receive your green card very soon. Good luck!
A: This questions has both immigration and real estate dimensions. Ultimately, the decision how/when to purchase a property will rest on your personal goals. Foreign nationals can purchase property in the United States. In fact, if you purchase together before the marriage, this may be a strong indicator of your bona fide intent to enter into a valid marriage. However, you must also consider that there are different ways of taking title in the US: tenancy in common, joint tenancy, and tenancy by the entirety (only available for married couples). Please consult an experienced attorney to help you navigate all these issues.
A: You need an experienced immigration attorney to review whether you husband is eligible for a I 601 Waiver of Grounds of Inadmissibility. If he entered without inspection, he must leave the US in order to apply for an immigrant visa at the US Embassy abroad.