Assalamu Alaikum
1. I pray 2-4-4-3-4 rakats, I read there are other rakats to pray, what is the number of rakat to have a valid prayer?
The correct order for the prayers is the following:
Fajr: 2 Sunnah Mu'khadda, 2 Fard
Dhuhr: 4 Sunnah Mu'khadda, 4 Fard, 2 Sunnah Mu'kkadda, 2 Nafil
Asr: 4 Sunnah Ghayr Mu'khadda, 4 Fard
Maghrib: 3 Fard, 2 Sunnah Mu'khadda, 2 Nafil
Isha: 4 Sunnah Ghayr Mu'khadda, 4 fard, 2 Sunah, 2 Nafil, 3 Witr, 2 Nafil
Prayers (Salat) are primarily of two types; (i) obligatory-
Fardh and (ii) voluntary(extra)-
nafil.
Obligatory or compulsory -
Fardh prayers are those which are to be offered at any cost what so ever and in any condition except when one looses its conscious. These obligatory prayers constitute
17 rakaat in number as follows:
Fajr: 2 rakaat
Dhur: 4 rakaat
Asr: 4 rakaat
Maghrib: 3 rakaat
Isha: 4 rakaat
Total: 17 rakaat
Voluntary (extra) -
nafil prayers are those which are not obligatory but are offered by some one at his free will, to please Allah.
These voluntary - nafil prayers are categorized into 3 types by Islamic scholars while emphasizing their importance;
a) Sunnah prayers, further classified into; i) Mu'akadda and ii) Ghair Mu'akadda
b) Nafil prayers, and
c) Wajib prayers.
Sunnah Mu’akadda prayers are those non-obligatory prayers for which the Prophet :saws: was very particular and he:saws: emphasized his followers to offer them. But one should remain mindful that to offer sunnah Mu’kadda prayers is highly rewarding but one is not accountable if he does not offer these prayers. These prayers are as follows:
Fajr: 2 rakaat ( before 2 Fard)
Dhur: 4 rakaat (before 4 Fard) + 2 rakaat (after Fard)
Asr: No rakaat
Maghrib: 2 rakaat (after 3 Fard)
Isha: 2 rakaat (after 4 Fard)
Total: 12 rakaat
Sunnah Ghair Mu’akadda prayers are those non-obligatory prayers which the Prophet:saws: was neither particular nor emphasized to offer them. These prayers may be as follows:
Fajr: None
Dhur: None
Asr: 4 rakaat (before 4 Fard)
Maghrib: 2 rakaat (before 3 Fard)
Isha: 4 rakaat (before 4 Fard)
Nafil prayers are purely voluntary but Islamic scholars, for reasons best known to them, have prescribed them as follows:
Fajr: None
Dhur: 2 rakaat after 2 sunnah Mu’akadda
Asr: None
Maghrib: 2 rakaat after 2 sunnah Mu’akadda
Isha: 2 rakaat after 2 sunnah Mu’akadda
Wajib prayer is also obligatory, but to a lesser degree. Witr prayer, after Isha, is considered Wajib by certain schools of thought, while some consider it as Sunnah Mu’akadda. Though its omission is strongly reprehensible, it does not specifically incur punishment.
2. After Fatiha, I recite An Nas, but do I have to do it for all 4 rakats or only 2 first?
When Fardh rakaa'h are four(in Zuhr,Asr' and Isha),this will be done for first two.
When Fardh rakaa'h are two or three(Fajr and Maghreb),this will be done for both.
Entire Salaah book
http://islamicbulletin.org/free_downloads/prayer/How_to_perform_Salaah.pdf
3. About praying out loud, when do we pray out loud? Is it really out loud or whisper? Can we pray silently?
Reciting Prayer Silent or/and Out Loud
And Allah Knows Best!