>>536203975
Most of them only show up around the starting areas that are located across the map. There's a bunch, sure, but there's also a bunch of places you get set down at.
>>536204047
Executor and Ironeye are the two classes who benefit most from upgrading their starting weapon assuming we're not talking about Revenan claws. Most of the time they start with some sort of benefit to them such as bleed, poison, holy, etc. You can upgrade those and use em' all the way through if you don't find something better.
It's also a good idea to do a quick mine run if you're near one, especially so if it takes you to where you're headed anyway, on day 1. Purple weapons are big on day 1 and you make up the time it takes to do the mine in the time it shaves off killing bosses.
>>536204257
all red bosses can spawn up there with the exception of the two dragons.