Teaching children discipline and respect

Q: I have two children Alhamdulillah. Both are boys age four years and two and a half years. Both are very naughty/aggressive by nature. I am trying to mange them but some times I feel that I am too strict with them so I try to change my behaviour, but when I change myself they became more aggressive and not ready to listen to anything. Sometimes it becomes really awkward and embarrassing when we (me and my wife) are calling them for something but they simply ignoring us and when we try to be little strict they (specially the younger one) starts shouting and crying for hours. Please guide me what Islam says about this situation? Is getting a little strict permissible or not? What is the best way treat a child?

Coming late for Jumuah Salaah

Q: Please can you advise if a person's Jumuah Salaah is accepted in the following situations and if not, then how should one make up for it:

1. A person arrives late and the first part of the khutbah has finished?

2. A person arrives late and the khutbah has finished, but manages to join in the first rakaah?

3. A person arrives late and misses the khutbah and first rakaah of Jumuah Salaah?

4. A person arrives on time for the khutbah but does not listen attentively to the khutbah.

5. Please can you advise if the second part of the khutbah is one which is read everywhere and does not change or are their different versions?

Web hosting

Q: We are selling dedicated servers to customer in the U.S. They purchase this service from us and than use it for their business, etc. We do not know what they will use this service for. They use the server for marketing etc. We do not sell such a service to the person who is going use it unlawfully and in a wrong way but when we can not recognise where they will use this service, than what can we do? Can we provide them hosting service? Is it permissible to for us deal with them? This server and hosting service can be use in both ways permissible and impermissible ways. It depend on customers usage. Please advise us.