Can a Landing Page reuse the main website navigation?
Sure it can but I would not encourage this.
Even Apple’s iconic product Landing Pages all have their main website navigation displayed when you first land:
but note how it disappears as you start scrolling:
Hiding your main website navigation will prevent a potential customer from wandering. Your Landing Page has only one objective — sending visitors to another page is not it.
If any of this (text, images or refs) didn’t make sense, please hit me up on Twitter or email - I’m here to help. Also let me know what Landing Page areas you are struggling with and I’ll try my best to point you in the right direction:)