Put your skills and fit in EFT and there is a two numbers just under you EMP resistances. This is your defence. Check out the FAQ.txt file within your EFT directory for some extra information.
But there is a things like your transversal speed, signature radius and overall speed, which can't be calculated by EFT. That's what makes T3 cruisers so effective, by the way.
Tech2 hardeners and T2 reppers is a must. Something better than that will help too. And of course, the skills. There is basically no "certain levels" for this skills, you will want to have them as high as you can(except for absolutely required skills, but they are usually those that you will need to level for efficiency of your tank.). Capacitor skills(Energy Systems Operation, Energy Management) is a must for every ship in EVE. And some extra specific skills, like Shield Operation+Shield Management for passive tank, Shield Compensation for active shield tank, Repair Systems for armor tank.
And by the way, 600 dps is a VERY solid tak, you will be able to clear anything in C3 anomalies. But it will take a LOT of time due to sleepers remore repping each other. So you'd be better to stick to C2s while going solo, it will be enough to tank 330 damage here, and you will have some space for damage mods, which will increase your damage. And if you are planning to go in with a friend, it is completely another tactics. Refer to "spider tank" for it.