Using a gray market phone

Q: I bought a brand new xiaomi smartphone in 2016. But the next year after I checked on government regulations website, my phone was "indeed" proven illegal. Illegal here means imported without any permissions from the government (not stolen, I already know the rules about stolen items). So no doubt about this. This leaves me questions:

1. What is the ruling for anything that we bought, we didn't know it is illegal at the beginning, but then it is proven illegal afterwards? (again, illegal here = "avoid taxes" not stolen items)

2. Am I allowed to continue using this or should I get rid of it?

3. What level of investigations should every Muslim do for each business transaction like this? 

Trimming the beard

Q: I am 18 years old and studying in 12th grade. I am growing a beard but my beard looks odd. I used gel to make it look straight but nothing happened. People everyday say me to neaten my beard and criticize me. Well all of these made me lose confidence. I dont want to meet people because they will criticize me. Can I just neaten my beard and will let it grow step by step?

Joining in a Christian prayer

Q: The below prayer is always said in my country (Ghana) in most gatherings. Please I want to know if it is good to join them and say the prayer as a Muslim because most people have belief that this prayer is found in the bible. So I want to know if it is permissible as a Muslim to say this prayer? Our Father in heaven, hallowed be your name. Your kingdom come. Your will be done, on earth as it is in heaven. Give us this day our daily bread. And forgive us our debts, as we also have forgiven our debtors. And do not bring us to the time of trial, but rescue us from the evil one.

Shias

Q: Shia's claim that their Kalima which they practice is in holy quran. Is it true? And As alot of scholars interpret and say that shia is not a sect but was a political movement of the kufies. To what extent is it true and if it is true,i would like to have a hadeeth reference about kufi ppl actually are the shia.