Fuji-Q tickets and travel

I'm going to visit the park in December for a day, but I'm trying to figure best route to go for tickets.

What would be easiest way to get there and purchase tickets from Shinjuku. I was thinking of the Q-pack for ease.

The main attractions being the roller coasters and maybe haunted house.

Issue is there will be three of us. Two of the group will doing rides, while third is just siteseeing and taking photos. We see that they offer free entry now if people just want to enter and pay per ride, which might be a good option for third person of the group. If the one person does the free entry, it saves money, but they might want to do the haunted house which is an additional fee.

Thanks for any opinions and help!