User Roles in Azure AD B2C and Azure AD

Dear All,
I am using Azure AD B2C for authentication purposes in my react and graphQL (Api).But now i have some doubts, Please help me as i am student.
My first doubt is that how can i add authorization in Azure AD B2C Please share some code sample?
My second doubt is that should i only use Azure AD for this authentication and authorization purpose or Azure AD B2C is better and may be cheap?
My third doubt is that is it possible that both Azure AD and Azure AD B2C can work together from existing user role sign in sign up and then i can use roles from token because it automatically attaches user roles in Azure AD?
My last doubt is that please recomment me how can i apply authorization and authentication on MS Azure (REACT - NODEJS(GraphQL) what is the best practice in this regard as i want to do both authentication and authorization in a possible cheapest way(price)?
Continuation ->
@Jamal Ashraf
My second doubt is that should i only use Azure AD for this authentication and authorization purpose or Azure AD B2C is better and may be cheap?
To answer this question, you can refer https://stackoverflow.com/questions/39271230/azure-ad-vs-azure-ad-b2c-vs-azure-ad-b2b which talks about difference between Azure AD and Azure AD B2C, coming to pricing
First - price is per monthly, active user (MAU). MAU means someone logged on at least once during the billing period (month).
Second - first 50k users in Azure AD B2C or external identities are Free. So first 50k users in a month, free - next are paid
Reference: https://azure.microsoft.com/en-us/pricing/details/active-directory/external-identities/#:~:text=Azure%20AD%20External%20Identities%20pricing%20is%20based%20on%20Monthly%20Active%20Users%20(MAU)%2C%20helping%20you%20to%20reduce%20costs%20and%20forecast%20with%20confidence.%20Benefit%20from%20a%20free%20tier%20and%20flexible%2C%20predictable%20pricing%20for%20external%20users%3A
My third doubt is that is it possible that both Azure AD and Azure AD B2C can work together from existing user role sign in sign up and then i can use roles from token because it automatically attaches user roles in Azure AD?
Yes it is possible, this article shows you how to enable sign-in for users from a specific Azure AD organization using a user flow in Azure AD B2C - https://learn.microsoft.com/en-us/azure/active-directory-b2c/identity-provider-azure-ad-single-tenant?pivots=b2c-custom-policy
Let me know if you have any further questions.
@Givary-MSFT
Thank you for your feedback! My concrete question is that i am applying authorization and authentication in our project, so what is the best practice to achieve this goal. I have go through with several things that in Azure AD B2C use api connectors to add information(roles) in the token or some other things i have also discovered like to not use user flows and use custom policies for this purpose. Now please let me know how can i achieve this goal of both authorization and authentication. What must be the best solution in this regard which would also be the cheap and best.