So changing the fluid again after driving for a bit would mean that any bits 'n pieces of gunk the first change didn't get rid of or were stirred up of would be flushed out the second time?
Well, actually the main reason is when you change the fluid only about half of it will flow out under gravity. A few litres are held in the torque converter and the galleries. Changing oil the second time means you should have no more than 1/4 of the old oil still in there.
And hopefully you will have taken out any gunk, but if the filters are doing their job no gunk should have been cruising through your transmission anyway. 
I'm hoping the same on the steering, but the mechanic doesn't give it much chance. He washed under the engine last week so the leak could be tracked then I took it back in yesterday for him to have a look. He let me under the hoist and it doesn't look good, but I did go for a bit of a drive on Saturday, so maybe fluid has just been spread around. He'll have more of a look tomorrow and I thought I might give changing the pump o-ring a shot, to start, then see if I think I can tackle hoses etc. *grin* only I'm gonna need a better socket set....
You can buy seals for the rack from the USA. It is a serviceable item. Mainly with steering rack leaks it is caused by the high pressure or return lines, and these can be fixed. The O ring is good to do anyway, but it will not be the cause of your leaking down below, unless you have loads of oil underneath the reservoir.
====
G'day to you too, Harvey and oh yeah, I'm a very happy chickie. Seriously can't wipe the grin from my face. Your posts and bits and pieces you've referenced have been really helpful, so thank you. I figure my best chance of keeping her sound, especially when the people that work on her aren't likely to know much about her, is to learn as much as I can and know what to look out for.
How on earth, with all that stuff I put down, did I manage to miss her kms???
184,500km
Yup, she is a bit off on 2-3 (positively pored over that recent thread). The revs do go up, though only a little. More pronounced is that its a slow shift and she seems to pull up a bit, more on light acceleration than heavier. Am I right that my model is rev based rather than speed based? Reverse is also slow to engage, 1-1.5 secs, and thunks a bit. 1-2 are fine, as is 3-4 I really don't know what sort of revs are 'normal' yet and haven't been able to find much info, other than it seems quite a bit higher than my previous car. (previous car is also the only other car I've owned - an '82 230E Benz).
Thank you for the tip on the radiator and the easy for a beginner to understand explanation - I've taken notes! Disappointment and a wounded wallet, from the sounds. I'm already skirting the outer limits of what was meant to be my budget.
Tania.