Plumbing – New washing machine using the same valve as the sink, water smells and tastes like plastic

Appliance parts like are generally specific to the manufacturer and possibly model. My usual approach, which has served me well, is:

1. Find the manufacturer's service website.
2. Do a parts search there, based on the model # and part description. Ideally, check the existing part for a label.
3. If that doesn't work, look for a parts diagram of your model. Often these include part IDs expressly for the purpose of ordering replacements.
4. Based on the part number identified in step 2 or 3, search on google and ebay for the part. Usually you can find it from a third-party retailer for significantly less than ordering direct from the manufacturer.

You might also try a local appliance repair parts store -- they may be able to guide you to find the right part if they are familiar with your brand of appliance.

I don't know of any specific schedule, but I can recommend several "best practices":

1. Buy braided hoses. These are the metal hoses with an inner plastic tubing. They are NOT guaranteed not to fail, but their failure is much less likely. Their most vulnerable failure point would be at the connection to the coupling.
2. Inspect the hoses annually.
3. Do not allow the hoses to kink - allow plenty of space for their installation.

Failed "fail proof" hose at the coupling:

You could also buy special high quality ($50) hoses - which frankly if you have a finished basement or your laundry is on an upper floor, is a sound investment in damage prevention.

Perhaps your BEST prevention, however, is an automatic washing machine shut off valve:

This device has an attached sensor (pic 2) which you set on the floor by your washing machine. In the event of a leaky washer OR failed hose, it senses the water and shuts off the flow at the source. For an under $200 investment, if you're protecting a $20,000 basement or worse, a whole house, not installing this once you know of it's existence would be downright foolish.