I wipe the pump parts with the Medela quick wipes between uses during the day, then rinse quickly (no soap) and steam in the microwave bag when I get home. I used to just use soap & water at home (no steam bag), but then one time I think I didn't get all the soap out and the milk looked too bubbly, so I dumped it - and I don't want to do that again. I also steam clean the bottle nipples that DS uses each day. I don't bother steaming the bottles anymore -- I just use soap & water & a bottle brush to keep them clean and residue-free.
The quick wipes come in 2 different size packages. The smaller size is cheaper per-wipe than the bigger size because the bigger size pack has each wipe individually wrapped and it comes with a free steam bag. The smaller size is just a resealable bag with a stack of wipes. I've bought both but I like the resealable bag (smaller size) better because the wipes are not as wet. The individually wrapped wipes have a smell to them that I don't like -- the smaller pack doesn't have any smell at all.
I have an extra set of 2 flanges/valves/etc for my PISA that I use when I'm home. They were pretty cheap at Target ($6.99 each?) and include everything -- the flange, valve, etc. They do not totally disassemble like the ones that came with the pump which is why I don't like to "travel" to work with them. It is nice to have a fresh set if I get home and want to pump an extra time for the freezer supply without cleaning off the ones I used all day.
I pump into the medela bottles and put them in the little insulated bag that came with the PISA. I throw in the special ice pack that came with the pump that hugs the bottles.