While you can get a Carnifex with Barbed strangler for an elite, I wouldn't suggest it, you still need to buy a 2nd weapon, and you may not have enough points to get enhanced senses after that. 2 sets of twin-linked devourers with enhanced sensed is a really good elite shooty carnifex.
For shooty troops, get basic gaunts. A lot of people give them devourers since it has the best range of all of their guns. I prefer without toxin sacs in order to have greater numbers of them.
You should get a tyrant guard or 2 for each tyrant to keep your hive nodes around longer too.
Also, get some spore mines for fast attack choices. They are cheap, and will aggravate your opponent since they can hit anywhere on the board.