Qiraat

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?

Reciting the “daal” in “wa lad-daaalleen” for less than 6 seconds

Q: I heard that when reading Surah Fatihah, you need to make the sound of the “dal” in “wa lad-daaalleen” longer, till 6 seconds. However, it is difficult for me to count how many seconds and often I finish it in 3 second or so. Is my prayer valid even if I do it deliberately because I can’t count seconds when reciting?

Repeating a verse of Surah Faatihah while performing salaah

Q: I heard in salah, errors to do with waqf dont matter. Does this apply to stopping in the middle of a word and then resuming?

I attempted reciting waladhaleen twice and every time between the ‘leen’ part, my voice stopped because of an obstruction in my throat. However, the third time I tried again and the same thing happened, after the pause, my voice came back a second later and finished reciting the remaining letters. Because I paused abruptly, is my salah fine?

Pronouncing few words incorrectly in salaah

Q:

1. I recited ‘saliheen’ with a bottom throat ‘ha’ and noticed during the middle of reciting it during the enlongation of the last syllable. During the elongation of ‘heen’, even after I realised, I still pronounced it with my lower throat. Is this considered intentionally reciting something wrong and did it invalidate my prayer?

2. During the du’a portion of Witr, I usually recite Rabbana Atina Fidunya 3 times. The second time I recited it, it felt like I had recited ‘Rabbana atina fidunya hasanatan wa qina adhabanar’ as opposed to the correct full invocation. Because of my uncertainty, can I assume my prayer is sound?