If my khums date is approaching and I have eatables or items that i will soon use like gas in my car is with me; is khums obligatory to pay on these items even tho they will be used soon?

You have to pay on that also .

Agar hm apni wajib namaze chair par baith kar padhte h(knee problem)to apne waldain ki qaza namaz bhi kya chair par baith kar padh sakte hai

Yes padh sakte hain .

ایک شخص کہ جو ہر سال خمس نکالتا ہے، اگر وہ ایک کار اپنے استعمال کے لئے لون پہ خریدتا ہے اور آئندہ دو تین سالوں میں اس کی قسط چکانے کا ارادہ ہے، تو کیا اسے اس کار کا خمس دینا ہوگا اور اگر خمس ادا کرنا ہو تو کس طرح ادا کریگا

نہیں دینا ہے

Is it okay to recite duas or supplications like from mafatih al jinan without hijab? Would there be any less of a reward or spiritual benefit for doing so without a hijab on? Sometimes it's just very hot or otherwise uncomfortable to do so.

No , not a must if no namahram is there.
In namaz hijab is must

Mustahab namaz chalte huwe padhi ja sakti hai? Us mustahab me namaze shub bhi shamil hai?

yes

آغا صاحب قبر پر شمع روشن کرنا یا جلانا کس حد تک صحیح ہے

شمع جلانا جایز ہے

Agar kapde ya jism ka koi hissa najis ho aur jiska ilm hone ke bawajood namaz padhte waqt bhool jaye aur namaz padhne ke baad yaad aye to kya namaz sahi hai ya phir se ada karni hogi?

Phir se padhna hoga

Husband khums nikalte hai but without calculation toh wife ke upar alag se apni chizo ka khums nikalna wajib hoga?

Wife ko shohar se bat karke calculation karna hoga aur sahi khums nikalna hoga

This year we came to know that if there are poor momin in your city, you cannot send your fitra to someone in other cities.But before this year we were not so clear with this, so we may have sent it outside.

No problem for those years when you didn't know the ruling

If we have water problem in the house and have to do wuzu from a bottle of water, can somebody help us in doing the wuzu by pouring water for us or we have to do it on our own without anybody’s help?

You can take help from others