I will start by saying that you should not be disabling auto-negotiation with Gigabit connections. This is what the standard has to say (from 802.3-2012 Section Three, which you can reference here):
37.1.4.4 User Configuration with Auto-Negotiation
Rather than disabling Auto-Negotiation, the following behavior is suggested in
order to improve interoperability with other Auto-Negotiation devices.
When a device is configured for one specific mode of operation (e.g.
1000BASE-X Full Duplex), it is recommended to continue using
Auto-Negotiation but only advertise the specifically selected ability
or abilities. This can be done by the Management agent only setting
the bits in the advertisement registers that correspond to the
selected abilities.
This means you should never use speed 1000 on Gigabit links. You could instead speed auto 1000, but your expressed need has a better solution.
The real problem is the following command on interface Gigabit0/0/0:
no negotiation auto
Remove the speed 1000, the duplex full, and the no negotiation auto commands from the interface and instead use negotiation forced so your interface looks like so:
interface GigabitEthernet0/0/0
description WAN Metro Ethernet Circuit
! ...
negotiation forced
From Cisco documentation, the forced keyword has the following effect (and I believe also adheres to the standard's recommendation):
Disables flow control and configures the Gigabit Ethernet interface in 1000/full-duplex mode.
This should meet your requirement of 1000/full with no flow control.
In re-reading your question, I realized you noted you did not seem to have the force command available.
In your case, I will still recommend removing the no negotiation auto command and have your interface look like so:
interface GigabitEthernet0/0/0
description WAN Metro Ethernet Circuit
! ...
speed auto 1000
duplex full
This is indeed a typical config, and most likely doesn't require you to change your hardware.
On one hand, you have the /30 which will be used on the point to point WAN link between you device and the first IP device on the ISP's side. So you should set your device up with the IP they gave you (.142) and a default route pointing to the ISP's device at .141
Then, they are saying they have assigned a /29 block go you. What this means is basically that there is a static route on their side pointing to you WAN IP (.142) for that /29 range such that any traffic for that range is sent to your router. At that point it's up to you to decide how to use it.
You can either route it to another device on your network (a firewall, say) with a static route, or use it on the router itself for handling NAT rules. The range does not need to be associated with any physical interface on the device: the router will be receiving the traffic anyway, due to the ISP's static route, it just needs to know what to do with a packet reaching it with a dest IP in that range: route it further, or process it.
Best Answer
You are on the correct path. The IP information is set on the interface, as you have already started. The default gateway should be the default route on the router. The DNS is set on the host.
Now the router should be able to access the internet. You will have to setup a few other things for hosts to access the internet, like private IP subnet, VLAN, maybe NAT and DHCP etc.
You can test the connection via the router CLI:
ping 1.1.1.1 source gi0/0/0