You just need to have something to raise the mussels.
Put a small dish upside down in your bowl, so that if grit/sand gets ejected it will not puddle in the dish.
Put your colander or sieve on top of the dish.
Fill with water put clams in the colander/sieve in the bowl.
Cook the meat in batches, 2, 3 batches so that the pan will stay at an appropriate temperature.
When you add too much ingredients, meat, vegetables..., in a pan, the temperature will drop and instead of pan frying you will be pan boiling.
I would do the following :
Cut and marinate the meat.
Cut all your vegetables.
Portion the meat to have 2, 3 batches (or ...
I recently repaired a global knife with exactly the same kind of nicks. Too small to feel with your fingernail, but definitely felt when cutting paper.
You'll need to re-profile the knife by using a coarse stone (even a brick will do). By holding the knife side perpendicular to the stone surface, and drawing from heel to tip, until the knicks are gone. This ...
Most people recommend A36 steel, which is a fairly common low-carbon steel. As far as I understand it (procured mine through ebay), you just need to work at scraping off the mill scale with some abrasive. Wash, dry, then season like a cast iron pan. After that you should be good to go.