jack1974, what regarding romance with Rumi? I didn't played Rumi's route, so I can't tell if there is CG available or no... And if we already have all kinds of combinations including Yuri and Yaoi, why not make Joshua x Rumi x Rebeca - I bet threesome will be awesome! Harem FTW!
I've also seen on forums somewhere you've asked about amount of nudity in game and about different restrictions in countries & etc. Regarding Nudity - make it more Hentai
The more eroge scenes will be in Visual Novel / JRPG the more people will be happy about it. Regarding restrictions in countries, you just can make in-game switch, that ask player if he is 18+ or less and then add to some scenes and game moments special flag, that will allow player turn off explicit content. By the way, it's how all ages version of Visual Novels done, developers just release same game, but 18+ version have special variable turned off, while all ages version have special variable turned on - in addition this allows people to switch back and forth whenever they want (if they found where variable lies, in most cases it's very easy to find)
jack1974, I also suggest you to play Visual Novel series Muv-Luv (Extra, Unlimited & Alternative), one of the greatest VN series I ever played with best character development. It definitely will help you with development of Planet Stronghold 2
and to everybody who wants to know how story and development should look in JRPG/VN. Extra & Unlimited took for me 20 hours each to finish and Alternative took for me 40 hours to finish.