Answer
(Fatwa: 1333/1330/N=1433)
(1) Giving khula on condition is invalid as per the Shariah.
ولا يصح تعليقه ولا إضافته بدائع (شامى زكريا 5 :89)
Khula cannot take place only from wife rather if she offers khula it is necessary for husband to accept it. So it is mentioned in the book of Fiqh. Hence in the question mentioned above, the letter of khula which your wife sent you with the signature of three witnesses as per the Shariah – though three years had passed – khula was not valid between you.
(2) Yes, she is still in your nikah provided you have not given any talaq to her.
(3) Until you do not give her talaq or khula is not done as per the Shariah or the separation in some particular cases is not carried out between both of you as per the Shariah by Darul Qaza or Shariah Panchayat and the iddah is not complete after any of the above mentioned matter, she cannot marry any other man and her nikah shall not be valid. Almighty Allah says in the holy Quran:
وَالْمُحْصَنَاتُ مِنَ النِّسَاء [النساء : 24]
و فى الفتاوى الهندية (كتاب النكاح 1:280 ط مكتبة زكريا ديوبند): لا يجوز للرجل أن يتزوج زوجة غيره وكذلك المعتدة كذا فى السراج الوهاج سواء كانت العدة عن طلاق أو وفاة أو دخول في نكاح فاسد أو شبهة نكاح كذا فى البدائع اهـ .
Allah (Subhana Wa Ta’ala) knows Best
Darul Ifta,
Darul Uloom Deoband