I own a 68, and am seriously considering an RS conversion. Someone told me I might be better off going with a 67 conversion kit as opposed to a 68 conversion kit. I'd rather check with those who know first. Any thoughts?

the main difference between the two years is the method of door actuation: electric motor ('67) and engine vacuum ('68). if you don't have enough vacuum, like from running a huge bumpstick, you might benefit from the electric motor, but there are ways to do that without having to buy a complete '67 set-up. retro-electric and dse make electric kits. the vacuum kit is bulky and not very attractive, but works.

The original 67 motors had their own problems...

There are several ways to use more modern electric motors that are more reliable the any of the original parts. Here's a thread about doing electric conversions:
http://www.camaros.net/forums/showthread.php?p=645968

That depends on if you are wanting it to look original under the hood or if you don't care and just want the headlight covers. There are unique advantages and disadvantages to either way. For the least amount of parts to change, the 67 has the advantage as it is more compact, but it would be very helpful to understand DC electronics to make it all work. The 68 system avoids the electrical, but all those vacuum hoses can be a hair puller if something isn't right. I think that a hole in each fenderwell will need to be added to make room for the door actuator pod. From what I have seen of the complete kits, they are good and with all due diligence, will serve you well. Personal opinion: go with what GM would have put in for your year. Years later viewers at the car shows won't be "informing" you of the error if you don't.