I think more details are required to help you troubleshoot these things you are asking?
If you have the trailer in front of you and can not tell for instance if the furnace
is connected or not we certainly will have no way of knowing this either,make sense?
There are many,many posts about Fiberstreams in particular and all trailer systems in general here on the site and I suggest trying to search or just just spending some time looking around to get familiar with the basic way these systems work in all trailers.
Most of these have similar workings really and so a general education about them will get you a long way.
The oven/heater you are asking about is a unique unit and only a few of us have seen or operated one,I have not. Mine has separate units.
That said though I would look and see where the connections are and where they seem to not be made,it should be rather obvious I think.
Again the brakes
are a system pretty much like most trailers but just telling us they are not working makes it a little tough to help.
Are they connected electrically,does your vehicle connector provide the voltage to even operate them,are the wires leading to the brakes themselves from the harness to the brakes inside the wheels intact and connected?
Normal troubleshooting techniques are the way to find these things out.
If you are not experienced or familiar with working on vehicles in general I suggest taking the trailer to someone who is to have it evaluated and this promises to save you time and aggravation though it will cost money.
Like anything else though the more information you have the better decisions you can make.
If I am off the mark then by all means give us some details and I am sure you can get some detailed answers in return but there just is not enough info yet to be able to help much.
As far as the weight
goes,you are in luck though.
Fred has a Fiberstream
and is a Professional Scale Mechanic too!
depends on what is in there of course but I know he has a good idea of the range you should expect.
I am sure when he sees this thread he will be happy to chime in as well.