Is the following statement sinful?

Q: My wife is pregnant Alhmadulillah. It's still the beginning of her pregnancy, but I try to buy the baby's things bit by bit to get good offers instead of buying everything last minute. My father told me not to buy so much yet and I answered something like "But at last minute one doesn't have all the money at one time". I know Rizq is from Allah and he could give me as much as he wants any time. What I meant is that I am planning on the grounds of what I have now (monthly). Is that statement and this approach sinful or even kufr? I regret saying it like that.

Performing Qadha Salaah instead of Sunnats

Q: I have many years of qadha salaahs. I need to know if I can read my qadha salaah instead of the sunnah salaah. I know that when I am a musaafir, I am exempted from reading sunnah. What about when I am a muqeem? When fardh salaah is more important then sunnah, then please advise if I can read all my fardh qadha salaah in place of my sunnah of zuhr, maghrib and esha.

Surah Faatiha in the 3rd and 4th rakaat

Q: I want to ask whether I have understood a masalah correctly: In a book it was stated that according to some Hanafi ulama reading Fatiha in the 3th and 4th rakat is Sunnah, and according to some Hanafi ulama it is Wajib.

Then the book stated if Fatiha is read twice in the 3th and 4th rakat, there no sajdah sahw by ittifaaq.

Do I understand correctly that sajdah sahw is not due by ittifaaq because whether Fatiha is Sunnah or Wajib in the 3th and 4th rakat, it is not Wajib or Fard to go to ruku after recitation of Fatiha in the 3h and 4th rakat and it is permissible to read more, but since it is permissible and not Wajib or Fard, there is no delay for the ruku, hence by ittifaaq there is no sajdah sahw due if someone reads Fatiha twice in the 3rd and 4th rakaat, whether reading Fatiha in the 3th and 4th rakaat is Sunnah or Wajib.

But in the 1st and 2nd since it is Wajib to read a surah after Fatiha one would delay this Wajib if one was about to read Fatiha twice hence sajdah sahw is due because of delay. But if one reads in the 1st and 2nd rakat first Fatiha then a surah then Fatiha again then there is no sajdah sahw because going to the ruku after the surah is not Wajib or Fard and it is permissible to read another surah after surah. Hence no delay thus no sajdah sahw.

Did I understand this masalah correctly?