The Ristretto was my first machine and I still have it for travelling. I have the steam through the showerhead issue but only after using the steam wand. When I overdosed with the presurrised filters I did get the problem with Coffee all over the showerhead and when I ground to fine or tamped to hard therfore choking the machine i got an explosion of coffee but never both together.
I gave up using the machine as intended, I used it for about 12 months but decided something had to change. I was going to buy a non-pressurised basket but in the end got an Aeropress
I now use this machine as a frother only. The SB and Areopress make a fairly cheap combination that can produce good coffee. I can also make mulitiple coffees fairly quickly when needed.
I know this doesnt answer your questions but I thought I would post some of my experiences too.