Linen is oldest fabric on Earth. If it would be so hard to be mainained than I am sure that it will not be known as oldest fabric on Earth. Due to its strenght it can be washed on cold or very hot temperature. If you remember stories being told by our granparents you for sure will remember that they were cooking their sheets, table maths and other fabrics. And then it was dried on the sun. And this is what linen likes. Linen does not like chemicals - use gentle washing powder. Linen fabric does not like crowd and when washed we need to make sure that our washing machine is not fully loaded. Also please use gentle spinning. If we put it into fully loaded washing machine on high spinning cycle than the fibre can be broken and broken fabric looses its characteristics. And before washing separate light and dark fabric.
When linen gets dirty - also count on its super power. No extra care is needed - linen will take care of it. Put some gentle soap on dirt as soon as it developes, don't let is soak deep into fabric - just don't rub linen - it will brake linen fibre permanently.
You can dry linen in your dryer on low temperature - just don't overdry it. It is best that you take your linen fabric out of dryer when it is still wet and hang or lie flat to finish process. Air drying is what linen likes the most. Sun is important part of flax/linen growing process and it helps remove stains from fabric. It is also more sustainable but this is your choice. The most important thing is that you don't overdry linen.
Linen can be ironed. If you dry it properly than no ironing is needed. As said high temperature can not do any harm to linen just with it it looses its wrinkle look.
Linen can be stored for years, just make sure that it is completely dry. And than it can last from generation to generation. In average with right care linen can last more than 20 years.