Some good questions there. For best hook size I do not look at this from the perspective of what is the best size to catch fish, but more or what will get the job done and more importantly what will do the least damage.
I love R&B 50/50 spoons for their weight, shape and movement. However, I hate the way they come with (IMHO) huge oversized 2/0 or 3/0 hooks. This may be ok for a large salmon over 10 lbs but anything smaller and you risk damage to an eye because of the hook gape.
Looking at intruder flies, which are often equipped with size 2 or 4 trailing hooks and they are very capable of bringing in a 20 to 30 lbs steelhead. So you do not necessarily need a big hook for a big fish.
As a result I change all the hooks on the R&B spoons for size 2 barbless hooks with the 3 split rings, which I can use for steelhead, Coho, Pinks etc, but I am also reassured that they can be used to catch way smaller fish like bulls or trout with less risk of damaging fish on a predominantly C&R river I like to fish.
As for pinks, I catch them on anything from size 1/0 jigs to size 1 or 2 on spoons and anything from size 4 to 10 on flies.
Sorry I'm note sure what you mean by width. Do you mean wire guage of the hook or the gape, as in distance between the point and shank?
I do not typically vary hook size based on pond, river or shore fishing. The hook size is based on fish size, species and need to match the "bait" or if I need to be stealthy.
HTH.