So far, your list looks like it would do well with Plague Marines and Berserkers in cc, with backup from the Space Marines with bolter fire. Defilers... generally do better in close combat, and you're really going to have to read up and decide a strategy with the Predator.
You can go ahead and build your spawns, they don't exactly get anything special as it is. Also, it's really simple to detach a bolter. So, if you wanted to give them any special weapons, all is not lost!
For the rest.. As Sanctjud said, you've got to make a decision of what type of army you want. From the looks of it [And IMO], it looks like you've got an army ready for close combat, and ranged shooting. You have enough Terminators to really do some damage, Plague Marines have blight grenades, which come in handy when you're being assaulted, and berserkers are built for cc! The Predator could provide backup from a long range, and the defiler could run up and punch stuff.