Ok, DHCP should be a setting on most routers (which the Homehub essentially is), stands for Dynamic Host Configuration Protocol and is basically a way of assigning a device a unique address to identify that device on a network. Think of it like a house. Every house needs a unique address so you get mail to the right house. This is true in the computer world also, the computer address is the IP address. This can be assigned manually by a network admin (ie yourself

) or automatically by a DHCP server. Your ISP (Internet Service Provider) will have a DHCP server that it uses to give you your unique address so you can connect to the internet with a unique address.
The port is like a door number. Imagine a big factory with lots of doors, each one is given a different number so workers know what the doors are used for - 1 - staff entrance 2 - main reception 3 - wood store 4 - cleaners cupboard ect. The computer is the same, uses different ports (doors) for different uses, 9000 is obviously a media port, say for example viewing U-Tube videos but it is configurable to any purpose, port 80 is used for viewing web pages and is usually set to this already.
A firewall is a security device that locks the port to prevent unauthorised access (like a security lock on a door). Port forwarding is the opening of the port to certain devices or services (like giving the cleaners a security pass to open the door to the cleaning cupboard, they can open it but nobody else can).
Hope this helps.
Regards, David.
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