The Drunken Lizard Pub

Noob question, sorry, but this is about when I see a creature for the first time in the game. I don't know whether I should flee or attack. At that point, can I gather any info about the creature, its attack strength, possible vulnerabilities and such?

You can do that very easily, attack, be attacked, look at the percentages.

If it's not in your favor, flee and come back later

Yep, "tactical retreat" is almost always possible

In Eschalon, it's really hard to run across an enemy that will trash you in one or two hits... so don't be afraid to "try out" a fight with a certain enemy. You can always run away and come back later with a bigger stick.