for food use spaghetti and meatballs and call it gaknar(?) from the klingon world. (Usually eaten while its still alive)
I'm sure a quick google of star trek food should yield results.
If he's got any star trekky stuff lying around use it in the decor.. hang up ship models, put his borg action figure standing on top of the cake...etc.
Put lights on magnets on the fridge (food replicator!)
hang gray or silver tablecloths on the walls and paint little lights and control panels on them
Have his favorite movie/episode playing in the background (or go film festival style and show them all)
as far as gifts, collectible action figures, tickets to a trekkie event, coffee mug with with a star trek quote on it. (Today is a good day to die. -worf, He's dead, Jim -bones, To go where no man has gone before....), tricorder cell phone case, a nerf gun hacked to make a phaser gun (bonus if it still works),
Have fun with this, I'm sure your boyfriend will love it!