In need of help with figuring out names and a few mechanics for a D% rpg

[Jay R]

Toughness(base stat); how do people feel about the name?

At least half your players will call it "Constitu, ... I mean, toughness". If you want Constitution, say Constitution. Filing the serial numbers off doesn't make it look less derivative. And there's nothing wrong with deriving ideas from earlier systems.

insects of some sort(I'm having a little trouble deciding which type of insect or arachnid to use as inspiration for them, I was thinking of maybe using a large beetle or a tarantula, or perhaps making a race themed off of both),

Decide what you want the race's culture to be like first, and then pick the insect or arachnid to match. A hive mind should be ants; a queen and slaves should be bees; a race of scavengers should be flies or roaches; a race of hunters should be tarantulas or wolf spiders; and a race of brooding waiters should be web-spinners. Use the qualities of the insect to make the race seem really inhuman, not just people in a funny body.

Any other ideas for interesting races are welcome.

Again, you're working backwards. Decide what a race should be like, and where it lives, and let that determine what they are like. If you want a hidden race deep in the world's greatest swamp, they should be amphibious - frog-like perhaps. Perhaps there are two races in a epic, thousand year-long war. They could be red and back ants, or possibly the same race with two religions.

Any time you have a new race, you should know why they are not humans. That reason is the basis that you will design the race around.

Also, how does "Veneficus" sound as a name for the system?

Like fake Latin, trying to sound like a word meaning "making something come", just as "beneficial" means "doing good", and "artificial" means "made by arts".

I recommend either a descriptive name, like "Dungeons and Dragons" or "Pathfinder", or a made-up word that doesn't have the form of a Latin word.