Qadha Salaah

Q: I have missed many namaaz in the past (as per my calculation 17-18 years namaaz). Now for the last one year I am regular in it. My question is regarding my qaza namaaz. I read that I have to perform my qaza farz namaz too. I read a short procedure of performing namaz too, in which I have to recite single time Subhana Rabial Azeem and Subhana Rabial Aalla only once, in Attahiyat short Darood shareef and in 3rd or 4th rakat Subhana Allah 3 times instead of Surah Fatiha, and Rabigfirlli 3 times instead of dua Kanoot. Is it valid? Do I miss my sunnatul Mukada and pray my qaza namaz and complete it as early as possible and then start praying my whole namaz after completing my all qaza namaz?

Being called while performing Salaah

Q: If a person is praying Zuhr salah at home and a family member calls him from another room, what is the best way to notify the family member that he is in Salaah? Is it ok for him to recite his qira'ah loudly for 1-2 seconds to show that he is praying (even if it is Zuhr salat), or should he say "subhaanallah" loudly or is there any better way?

Extended warranty

Q: Is it permissible to purchase an extended warranty at the time of purchasing the item (in such a manner that the fee for the warranty will be regarded to be part of the purchase price of the item)?

Pension fund

Q: In addition to the Provident fund question asked, does the same apply to the Pension fund? How will I know if and how much of interest has been accumulated over the years and how do I calculate? Do I ask the company how and where was my pension fund invested.