Usually the more rev's you stack, the more sluggish the kites become. They also pull like a truck, especially when you start to get over 4 kites. Even my 5 stack of Rev II's can have some solid pull in them when the winds pick up.
For a 6 stack, I would suggest a minimum of 250# lines, I have 300# lines on my 8 stack of 1.5's. I have buggied with it in 10 mph winds. LOL
There are a lot of tuning you can do, most of the tuning is to get the stack to follow correctly and get more precision out of it. I have found on nearly every stack I have done that you will need to pull in the top lines at least 2 inches, probably more like 3 or 4 inches to get the best control and ease the pull. This lets you fly without ripping your arms out of their sockets, but more importantly, makes the stack behave much easier. Without pulling in the tops, the stack will always try to flip on you when hovering or stalling/landing. Small stacks like 2 or 3 can hover pretty good when tuned in properly, more kites than that then you will probably not want to try hovering them at all.
Tuning in the stack can take a very long time to do but it is soooo worth it in the end. Start with all stack lines equal (*except the center ones, those are always going to be different depending on how you attach the front kite to the next and so on). Fly the stack and then adjust the lines as you see necessary depending on how the kites are behaving. Usually I pull in about .5 to 1 inch on the very last kite bottoms, this usually helps with the 'chasing' and keeps that last kite more in check. That's a good place to start and then work forward as needed.
As for frames, with a 6 stack you may need to beef up the front kite or two with either the 4 wrap SLE rod, or contact me and we can work with Rev to custom build you a couple stiffer rods, like 6 wraps or something. The reason you need to beef up the front kite (or two) is because all the other kites are hanging off of the front one and it is in a constant tug or war between the flying lines and the rear kites. This puts a ton of stress on the frame. If stacking less than 3 kites then you can usually use whatever frames the kites come with, more than that you may need to beef them up. As you are stating lightly, meaning light winds (I assume), you may not need the extra strength frames, but if a gust hits you may be in trouble.
Hope this helps, let me know if you need any other info and I will help out as much as possible.