I am going to work to answer the question I see as the less opinion-based portion of this question that is friendly to this format.
What factors are important to determining how a settlement/community would respond to player's actions?
For the purpose of this answer, I'm going to focus on the murder. The framework outline is adaptable to other situations. You've already answered some of these, but I'm going to walk through the whole process.
The primary things that need to be considered are:
- How large is the community, and how easy would it be for someone to
- What is justice (as abstract and process) in this
community? Who enforces this?
- What was the victim's place in the
community? How was the victim perceived by the rest of the
These three points will inform what other questions you need to ask yourself to make a decision, and can sometimes be enough for you to have an answer.
I'll use an example from a setting I'm working on right now:
- The rapidly growing city of Northern Reach has a growing, though still small, city of about 8k. Many people in this town are newcomers, outcasts attracted by the resource boom (a mixture of lumber and mining), but if there is anything really distinct about the party this may not matter (such as strange races, which my players are generally really fond of).
- The administrative leadership is places value on lawfulness and goodness, but justice is determined primarily by the Captain of the Guard, who is less concerned about goodness and more concerned with everything running smoothly.
- The person killed is related to some of the higher-ups in town administration, but is not generally well liked and known to be something of a cheat.
From this basis how things proceed is easier to determine. The captain of the guard doesn't terribly want to fight the party, who we will assume for this exercise are reasonably well armed and appear to be competent in combat. He needs to do something, and the legal penalties have not been revealed to players prior to this point (so there's still flex room for adjustments if needed for the group)
The players appearing to have wealth gives him a way to keep things running that may be easier than other options, so I will have him approach the party with the accusations and judgement (as well as enough additional guards to back him up as are needed). I have a fondness for old Germanic/Scandinavian law, so what I will do is charge weregild for the deceased (proportionate to their social role, to appease the minimum legal requirements), as well as a fine (bribe) to let the matter be dropped on this first issue. The fines should be enough to make the players consider consequences in the future, but not so much they feel it's worth a (possible) TPK. I would also play it to communicate that if they are tied to further problems in town matters may be dealt with more harshly.