New to this...

it's really impossible to answer your questions since requirements will vary by location, not just country but possibly state/province.

generally speaking, you will need a captains license. in the US that woudl be an OUPV aka six pack if you don't carry more than 6 passengers. more than 6 passengers and you need a Masters (need to be US citizen for the master though). over 6 passengers the boat need to be USCG inspected which includes many safety modifications like higher rails, fireproofing, etc...

there are no issues with alcohol on charter boats in the US unless some locations may have local rules.

overseas or with non US flagged boat, it's all different. generally speaking a US flagged boat with a US license captain can operate some charters in many places (Bahamas, Caribbean, etc...) unless you're looking at running a local business where the boat is tehre all the time and runs day charters. then it becomes a local business subject to the rules of the island you operate on. but for weekly charters, you can pick up guests in foreign ports.

insurance, it's hard to tell ... so many variables. i woudl guess $6k to $10k a year dependign on boat value, location, etc...

your biggest hurdle is going to be getting a license "being new to this". you need experience before you can even get one. insurance will also require that you have enough experience, especially for charters.

and running a charter is a lot different from running your private boat. you need to know what you are doing, and look like you know what you're doing. you need to be able to face whatever issue (weather, mechanical, etc...) since you are responsible for your paying guests. it all requires a much higher level of capabilities than running your own boat.

it's not impossible though, but it won't happen over night. you'll need a few years running the boat on your own, learning, before you can really consider running the boat on charters (unless you hire a captain)

mikey_mike1234, Welcome to YF.
Let me ask a few questions:
1) Where do you want to do this?
2) What kind of experience do you have on the water?
3) Are you looking to do a crewed or bareboat charter.
40' is a tight place to live with 6 strangers. Remember that 'fish and houseguests tend to stink after 3 days'.