the Cambridge does include a test to comply with the new rules that at all qualifications that can be included in the league tables have a exam element to them. The test is unit 1 and is 25% of the final grade, with the rest being made up of coursework. All new spec BTECs are also running in the same fashion.
The Business Communications is a mix of business and ICT. They have to have basic business knowledge for 50% and then use ICT skills and knowledge for the communication part.
Business and Economics is part basic business knowledge, i.e. marketing mix, recruitment, basic finance etc and the 2nd part pure economics
As Blissx has said, business and ICT are usually within the same faculty and you will find that the vast majority of business teachers also teach ICT at some level. My background for example is 50% computing/electronics/ICT and 50% business (my pre-degree qualifications are pure electronics and computing to HNC standard and then A levels in business and law; my degree is Business and ICT so I am qualified to teach ICT, computing and business).
Computing is a 'new' qualification at this level and therefore is not offered at many schools currently it is very quickly gathering pace with the recent inclusion as a science for the Ebacc. There are teachers within schools who can deliver this subject, but not many given that a lot of ICT teachers are in a role that they have no degree/qualification for but just as they showed an interest in ICT.
For the subject of computing to be offered at the majority of schools, there needs to be a lot of retraining not only for those not qualified, but also for the like of me who has not had to use their skills/knowledge for so long as we have had to deliver the rubbish curriculum as prescribed by the old NC/specs.
I will add though, the latest Edexcel spec for GCSE ICT is a lot more interesting and relevant and not as easy as people believe!