Permissible and impermissible items of trade

Q: Why is it haraam to sell dogs?

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? 

Q: Is it permissible to sell cats?

Q: Is it permissible to sell firecrackers?

Q: Is it permissible to breed and sell freshwater and aquatic snails? People keep these type of snails in their fish tanks. I do not think anyone (Muslims and non-Muslims) eat them in South Africa.

Q:

1. If you do good deeds like fasting, salah, etc. but at the same time you have a business which sells alcohol or where you work sells alcohol, would Allah accept your good deeds like fasting, salah, etc?

2. Also, is selling alcohol the same as drinking it?

3. I heard those who drink alcohol in the dunya (world) wouldn't drink wine in Jannah, does that apply to people who don't drink it but sell alcohol?

Q: Is it permissible to sell saaris in South Africa?

Q: What is the ruling on selling expired goods at a Muslim owned store? Customers are not told that the goods are expired and when they had expired.

Q: What is the ruling on selling electronic cigarettes, an alternate for smokers.

Q: If a house is under the spell and effect of magic and jinn and if, for this reason, the houseowner wants to sell it out, hiding from the buyer the fact that magic and expecting a good rate from him, would it be permissible for him to do so?