1. Lotus Lake will become a full-fledged nation and have available girls starting from Lamium's event (event #54, so about two-and-a-half months later). This will also clear the fog over it, making landmark descriptions readable.

There are no available knights from Kodaibana, although some girls like Lavender previously lived there, and story-wise there is an ongoing effort to push back the pests and reclaim the place (detailed in Skullcap's event and a recently announced light novel).

2. Cold-associated knights usually belong to Winter Rose, although they are mostly based on plants like wintersweet, poinsettia and Christmas rose rather than true tundra-dwellers (there's also Ghost Weed, a knight who is really not good with the cold, but was assigned to Winter Rose anyway because her name sounded winter-y).

Desert plants are likewise few in number and mostly include cacti, but with Lotus Lake being based explicitly on Egypt, we might see a group of them over there (then again, so far only Adenium/Desert Rose is a desert-themed LL native). It's worth noting that flower habitats in general don't match one-to-one with their nations, with the exception of Lotus Lake, which has a pronounced focus on aquatic plants.

3. Sarracenia and Catchfly are currently the only knights based on insect-catching flowers. Both have their flowers' habits reflected in their character designs: Sarracenia digs pitfall traps and lures pests to them, while Catchfly carries a butterfly net and is really into capturing and dissecting pests.

Sarracenia's love of booze may also be a reference to the fact that some pitchers are known to drug their prey, although a pun on her name probably has a bigger influence here (heishisou is an alternate name for trumpet pitchers, and the vases she's carrying are heishi sake vessels). By the way, Nazuna herself is based on an arguably semicarnivorous plant, though the real reason that she's the game mascot is probably that she has a very fitting flower meaning ("I offer you my all") for an assistant knightmaster.

As for pollination traps, we do have a few knights based on flowers with them, like Heart Vine, Royal Water Lily and various orchids, but none of them reference the process in their design (except possibly Royal Water Lily, whose bloodthirstiness may be derived from the tendency of waterlilies to capture and drown small beetles in their mucilage pits, although that's a bit of a stretch). Some knights (like Christmas Haretail Grass, Christmas Begonia, Iberis and Calceolaria) also have attack animations that involve tossing a bunch of presents/stories/candy/other stuff at the enemy, while Golden Lace has portals as her main theme, but their attack animations aren't too close to what you've described.

(And speaking of pollination traps/knight types we'd like to see, I've been wanting an Ophrys-themed puppeteer for a very long time now. This is an orchid that imitates the shape and smell of female insects to attract males and pollinate itself during "mating", so it makes perfect sense for a knight that controls female pest dolls to trick pests into attacking each other).

4. EN FKG is ten months behind the Japanese version.

5. Well, that's something I can't help you with. Sorry.