I'll reply here rather than on my old thread.
The intermittent pumping sounds upon starting the shot is normal, it's the preinfusion function. The manual function does not use preinfusion.
Steam problem sounds like a dodgy control board, probably heat related. You could remove the board and see if there is any noticeable damage or cold solder joints. Aside from that it would be time for a new board. You could try replacing components but that isn't a job for you if you don't have experience.
Corrosion on the lower half is most likely due to the steam baffle leaking water/steam out into the chassis rather than fully into the drip tray. This baffle is located behind the grey plastic panel on the right hand body panel. You should be able to see if it has been leaking.
You can epoxy the leaks or buy a new baffle.