Hi David,
I see what you are talking about now. Looks like the hose goes over barbs on the connections. Easiest way to remove is to carefully cut the plastic tubing over the barb. I would not cut through the tubing, just score it deep enough so that it is easier to take off. And yes, to install, soak in hot water as Pawell recommends. Plastic will soften dramatically with higher temperatures and how plastic is molded in the first place. You don't want really hot and not above 170*F. Above 200*F, most plastics will melt.
The check valve on the car is the original style. If you want to keep original, you can easily test that to see if it works. The replacements I have seen fit just fine but are different in appearance.
BTW, you can buy transfers for your Bosch relays that has the part number on the front and wiring schematic on top. I think Bud's Benz has them. They are dry transfer and easy to install.