Hi Declan,
What you are seeing is as expected - the warning about committing to the trunk is normal. Every suite has a trunk and it is this that you will be committing to. When you are asked to confirm if you wish to commit your changes just say yes (y). You will then be able to copy your suite u-cq558 to a new suite including the changes you will have committed.
When you copy a suite either in the rosie go GUI or on the command line with rosie copy <suitex> this copies to a new suite id and makes you the owner of it. Only the suite owner can commit to the trunk unless you explicitly give permission to other users, so don’t worry that you are committing to somewhere you shouldn’t be.
Don’t worry about branches where suites are concerned, they are mainly used when more that one person is developing the same suiteid.
Cheers,
Ros.