Be specific on what you want. If there's something like "this watch goes on this characters left hand, not their right" please remember to bring that up. I don't read minds and I don't wish to either.
My base prices are for one character with no background or a white background. If you want extra characters and a background it will be extra. Not much extra though it all depends on what you're asking for.
I've got no problem with pin up or "ecchi" but I may refuse if I don't feel comfortable with what's being asked for. Which is typically explicit stuff as opposed to pin up.
Remember my strength is character design, if you want me to do something like a giant robot I'd suggest pointing me to or sending me whatever references you think will help.