Salah (Prayers)

Bismihi ta'ala

I will list only the daily nawafil:

Nafilatul-Layl:
Amount: 8 rak'ahs. 
Time: Before Fajr time.

Nafilatul-Fajr:
Amount: 2 rak'ahs.
Time: after fajr time, before salat al-fajr. 

Nafilatul-Dhuhr:
Amount: 8 rak'ahs.
Time: dhuhr time, before salat al-dhuhr. 

Nafilatul-'Asr:
Amount: 8 rak'ahs.
Time: after dhuhr, before salat al-'asr. 

Nafilatul-Maghreb:
Amount: 4 rak'ahs.
Time: after salat al-maghreb. 

Nafilatul 'Isha`:
Amount: 2 rak'ahs. 
Time: after salat al-'isha`, sitting down.

Bismihi ta'ala

If you pray the nafilah prayer, then that is the mustahab thing to do, to pray it on its time, and then pray the wajib prayer, and with doing this, you will not be deprived of anything. 

You will gain the reward of the nafilah prayer, and the reward of praying on time, which in reality that is what you are doing. 

Therefore, there is no need for you to pray the nafilah prayer before its allocated time. 

And Allah knows best. 

Bismihi ta'ala

There are a few highly recommended things at the time of iftar, when you are going to break your fast. 

1. Praying on time. Prior to adhan, be ready for prayer, so when you hear the adhan, you pray on time. 

2. Before you break your fast with food/water, recite this:

اللَّهُمَّ لَكَ صُمْتُ وَ عَلَى رِزْقِكَ أَفْطَرْتُ وَ عَلَيْكَ تَوَكَّلْتُ

Allaahumma laka sumtu wa a'laa rizqika aftartu wa a'layka tawawkkaltu

O Allah, I fast for You, and I break the fast with the food You give me, and I rely on You.

There is another narration, from Imam Ali (a.s.) that says when he broke he fast he would say:

بِسْمِ اَللَّهِ اللَّهُمَّ لَكَ صُمْنَا وَ عَلَى رِزْقِكَ أَفْطَرْنَا فَ‍تَقَبَّلْ مِنّٰا إِنَّكَ أَنْتَ اَلسَّمِيعُ اَلْعَلِيمُ

3. Once you recited this dua, recite Surah al-Qadr, and then break your fast.

4. It is also recommended to pay sadaqah at the time of iftar. 

With prayers for your success.

Bismihi ta'ala

Engaging in haram acts does not mean one abandons their devotion to Allah ta'ala and their 'ibadah. 

Indeed, it is even more important to stress on that, for the purpose of hopefully empowering oneself to become more obedient to God and stay away from sin. 

Yes, this man should continue to pray, fast, and perform everything else required by him as a Muslim. If done in the correct way, they will also be valid as well. 

With prayers for your success. 

Bismihi ta'ala

Numerous reverts I have interacted with did face similar issues, where they feared backlash, and had to conceal their Islam. They would pray in secret, and so on. 

In answering your question, in your circumstances, your prayer will indeed be valid.

What I would like to recommend is that you correspond with other fellow reverts from your same background, and find feasable ways in how you are able to overcome some of the struggles and difficulties you might be facing. 

May the Almighty give you strength, and bless you for your accomplishments.