(1) Is it possible for a Wali (a friend of Allah) to know things through Kashf? Is it possible for him to know whether or not he or someone else is destined to be in Paradise? If this is true, the can you please provide proof for this?
(2) Is it permissible to supplicate to Allah, saying, " Oh Allah, show me in this world the person who will be with me in Paradise".?
It is not impossible for Allah to reveal to someone of close proximity to him that he or someone else is destined to be in Paradise. In fact, Allah may reveal hidden matters to whomever he wills. However, it is not recommended to supplicate to be shown the person with whom you will be with in Paradise, rather, one should supplicate for you and that person to be united in Paradise.
ففی الفقه الأكبر: والكرامات للأولياء حق الخ (ص: 51)۔
وفی أصول الدين عند الإمام أبي حنيفة: وكذلك يثبت أبو حنيفة الكرامة للأولياء، و هي أمر خارق للعادة يجريها الله على يد عبد صالح متبع للشرع غير مقارن بدعوى النبوة الخ (ص: 478)۔
وفی شرح الطحاوية: قَالَ أَبُو عَلِيٍّ الْجُوزَجَانِيُّ: كُنْ طَالِبًا لِلِاسْتِقَامَةِ، لَا طَالِبًا لِلْكَرَامَةِ، فَإِنَّ نَفْسَكَ مُتَحَرِّكَةٌ فِي طَلَبِ الْكَرَامَةِ، وَرَبُّكَ يَطْلُبُ مِنْكَ الِاسْتِقَامَةَ. قَالَ الشَّيْخُ السُّهْرَوَرْدِيُّ فِي "عَوَارِفِهِ": وَهَذَا أَصْلٌ كَبِيرٌ فِي الْبَابِ الخ(ص: 495)۔