Karl Hockless
As has already been posted by the majority of other experts, you should be able to find a company that can do the whole project for you. The main benefit of using one company is that all the various task elements will be integrated, meaning everything should happen smoothly, on time and without confusion. Trying to organise lots of different, separate trades people who haven't worked together before will give you lots of problems. If the dividing wall is stud then it is very easy to remove. However, if it is a supporting wall you will need to have a support installed - probably a steel RSJ. In this case you may also need to obtain structural engineers calculations and also pay for an inspection by the local council's building inspector. Any electrical work will also need to be certified prior to the building inspector being able to sign it off. Hope this helps, Karl