Hi, my wife's 2003 W168 LWB 170 CDI has been casuing me problems for a couple of months after about 1/2 mile of driving - usually just after she hit's dual carriage way from our house, the gearbox fails to change up as expected and then wont rev harder than 3000 rpm (no F on the dash though

)
After covering off usual servicing items, I made a home made dispstick for the ATF from curtain wire and discovered that the fluid is as far as I can tell about the right level - but absolutely cooked.
Despite Mercedes suggesting this is a service free box, I want to change the fluid in the gearbox.
Q1: From my reading so far the Automatic (not semi) in the W168 is the 722.7 model is this right ?
Q2: I can find no reference anywhere (in english anyway) that tells me which ATF spec is required for the A class - note I have seen several people say use only mercedes spec, which is all well and good but I am planning on doing this job running it for a week and doing it again to flush it thouroughly and a buddy of mine can get me ATF fluid by the bucket load so I would like to do at least 1st attempt on buddies free fluid.
Q3: Does anyone know what the fill capacity is on this gearbox ?
Q4: Do you know anyone in the UK that supplies the dipstick ? I found someone in the states that will supply but including postage they want nearly $100.
All help will be gratefully appreciated.