Hello,
Yes, it is possible to change the “Login/ Register” to ‘SIGN IN / REGISTER’ and change Login to “Sign In”. To achieve this you need to use the Loco Translate plugin, from your dashboard you have to go to Loco Translate >> Themes >> WoodMart >> Edit your template >> Search for your strings and change them, and save the changes:
Screenshot for your satisfaction: https://jmp.sh/hd1avW6
Result: https://jmp.sh/EJOAlvf
You can check and follow the below video tutorial for Loco Translate:
https://youtu.be/D3NsDdMzsls
With the theme options it is not possible to add First and Last name field in REGISTRATION form and set the first name default as the Display name. It requires customization and this is beyond our limitations and support policy.
You can try some third party plugin for this purpose.
Best Regards.