High-Quality Image Edit and generating background

I have three image editing tasks:

1. Cut out the two people from the original image with very precise, clean edges, especially around the hair. The cutout must be delivered as a high resolution TIFF file with a transparent background.

2. Generate two different realistic backgrounds according to my specifications (sunrise in the mountains)

3. Create two final images by professionally combining the two people with each of the two newly generated backgrounds. Both results must look completely natural and photorealistic, with realistic lighting, depth of field, colours, shadows, perspective, and seamless integration of the subjects into the new environments.

FINAL DELIVERY REQUIREMENTS:
• Two different final images with two different backgrounds
• Final image size for each image: exactly 5464 × 8192 pixels
• Resolution: 300 dpi
• File format: TIFF
• Full resolution and maximum image quality
• The final TIFF files must contain genuine high resolution image data. An upscaled JPEG converted or saved as TIFF will not be accepted.
• No visible cutout edges, halos, or artificial looking transitions
• Natural and realistic integration of the people into both backgrounds
• Both final images must be suitable for professional high resolution use

ATTACHMENTS:
• fl1 = cut the people out
• fl2 = preview how the result could look like

DEADLINE:
Both complete final images must be delivered within 24 hours, no later than Thursday at 12h CET.

I look forward to working with you :)