Not to be a smarta$$, but what you have there is cake compared to a v8, for the simple fact that you can get at the work easily. I'm a mechanic in the rust belt and just about every ford and dodge truck with a v8 has broken/rusted manifold bolts. With them you have to raise the engine off the mounts, use a 90 degree angle drill, and squeeze your hands in between the head and frame rail just to work on the thing. I only do about 1 a week (that's all the patience I have) so I'm pretty good at doing it. So here's a few suggestions.
I've never had an EZ out work, regardless of the brand. Usually if it came out with an ez out, it would have came out with a vice grips or left handed drill bit.
I've used cobalt drill bits with good success, all the carbide bits seemed to be too brittle to use with anything but a mill. Stay away from your coated hss bits that you can get at the hardware, it might work for the first bolt but the coating will wear off easily, also hardware store bits aren't the best quality in the first place.
If you think it is rusted, heat and penetrating oil will be your best friend. PB blaster is good but I prefer aerokroil. It just seems to work better. If the stud isn't broken flush with the head, get a good visegrips, heat the head up with an acetylene torch, quench the bolt with penetrant, and than turn the stud out with the vice grips. It takes a certain feel to figure out if it's going to come out or snap off. So don't be afraid to heat it up and or quench it multiple times.
If you have a good 220 welder you can try and weld a nut on there, especially the bolts that aren't snapped off flush. It does work but it requires practice and good equipment. I"ve only done it a few times because with the pickups you can't get a welder in there to do it.
If you're going to drill it out, use left handed bits. Making sure the bit is centered is very important, so grind the end of the bolt flat to the head. I then use a 3/16 x 60° single flute uncoated countersink. It has a sharp point and is very good at creating a center. They seem to work better then center drills do or just trying to free hand a regular bit. You can get them at any machine shop, or from here http://www.mcmaster.com/
part # 3285A32 . Then you will use a small bit, and size by size work your way bigger until it screws out via the drill, or you have the whole bolt drilled out.
Any other questions or tips you can pm me.