1. First things first, make sure you've got the Firebase CLI installed. If not, just run:
   ```bash
   npm install -g firebase-tools
   ```
2. Next, log in to Firebase with:
   ```bash
   firebase login
   ```
3. Now, head over to your project's root directory in the terminal.
4. Time to initialize Firebase Hosting in your project:
   ```bash
   firebase init hosting
   ```
   Follow the on-screen prompts to pick your project and set up the options.

firebase.json is right there at the root of your project directory. This file holds all the Firebase Hosting configuration details.

1. In firebase.json, find the Hosting section.
2. Add the redirects array inside the hosting configuration:
   ```json
   {
   "hosting": {
   "public": "public",
   "redirects": [
   {
   "source": "/old-url",
   "destination": "/new-url",
   "type": 301
   },
   {
   "source": "/another-old-url",
   "destination": "/another-new-url",
   "type": 302
   }
   ]
   }
   }
   ```
   • source: The old URL path you want to redirect.
   • destination: The new URL path where the traffic should go.
   • type: Choose 301 for a permanent redirect or 302 for a temporary one.

1. In the same hosting section in firebase.json, add the rewrites array:
   ```json
   {
   "hosting": {
   "public": "public",
   "rewrites": [
   {
   "source": "/app/**",
   "destination": "/index.html"
   },
   {
   "source": "**",
   "function": "app"
   }
   ]
   }
   }
   ```
   • source: The URL pattern to match.
   • destination: Used to serve a specific file, like index.html.
   • function: If you're using Cloud Functions, specify the function to handle the request.

1. Save the changes you made in firebase.json.
2. Deploy the updates to Firebase Hosting:
   ```bash
   firebase deploy --only hosting
   ```

After deployment, Firebase will serve your configured redirects and rewrites as specified in firebase.json.