Lifting one's foot during salaah

Q: I read somewhere that you cannot lift your foot in prayer and it invalidates the prayer. But when I stand up from the sitting or prostration posture, I need to adjust my feet so that I am again facing qibla directly (my body seems to be a bit lost of the previous position). I heard it invalidates prayer. Hence if I am very slightly not facing qibla, I would just not lift my feet to adjust it. What should I do? 

Using computer software codes that have Greek names

Q: I'm a computer scientist and in my learning and use, there are often libraries of codes which are very popular and heavily used. They often contain a lot of math or pre built software. The problem is that the library sometimes might have a haram name like jupyter, greek mythology names much like the names of several planets. What should a Muslim to do in this situation?

Hiring a cold room

Q: We find it is becoming common for people to hire cold rooms, refrigerated trucks or trailers for Eid. These equipments are hired out to anyone and have most likely been used for haraam meat before.

1. Could this cause contamination although the meat is not being stored in it at the same time as the haraam meat?

2. How should one go about cleaning the equipment prior to using? Is there a specific manner and specific number of times in which it should be cleaned?

Keeping in contact with one's daughter who became a Christian

Q: Alhamdulillah I'm married to a Muslim widow. My wife got 3 children from her 1st husband. One of her daughters got involved with a non Muslim and she became a Christian. She left Islam about 10 years go. Me and my wife tried so much to bring her back to Islam, but she does not want to accept.

Now my question is, does Islam allow my wife to still be in contact with her murtad daughter? Do I have the right as a husband to stop my wife from keeping contact with her murtad daughter? 

How much longer should the first rakaat of salaah be?

Q: I know that one should read longer Qiraat in the first rakat than the second rakat and that one should not skip an in-between Surah between rakats unless the rakat one skips is long. This applies to Fard salaah. My questions are:

1. What is meant by "long" Qiraat? Is this the number of lines or the number of ayaat?

2. Does the Qiraat have to get progressively shorter for the nafl and Sunnah rakats of Sunnat-e-Muakkadah and Sunnat-e-Ghair-Muakkadah as well?

3. Can you skip an in-between Surah in the Nafl and Sunnah salaah?