Rust prevention questions

[mnz28]

 Hi all,
I am considering buying the 5 pc cab repair kit listed here http://www.73-87chevytrucks.com/
The truck is a 1986 K-10 4x4. I will describe the parts as best I can.
1. What is behind the cab corners as it feels like something is still there? Was a brace used behind the cab corner?
2. When inside the truck the floor doesn't feel like its bad and appears solid from underneath, but on the kick panel vent area I have a 2" high area on both sides that is questionable. Will the repair kit fix this or is another panel available elsewhere to fix this issue. If you could post a link it would be appreciated.
3. What causes the cab corners and rockers to rust out? I am thinking debris get trapped and causes the rust. I see this is a common issue on the majority of trucks. Are drain holes drilled in the rockers and cab corners?
4 What tricks or tips would you give to rustproof this area in the future.
5. Any advice for installing this kit or feedback on what you thought of it.



3.

[Blazin]

You can make the kick panel pieces, they are almost flat. Where they meet the floor they have a little off set toward the outside of the truck.
There is an inner cab corner, and an inner rocker. the floor comes with part of the inner rocker as part of it.
The inner rocker is open on the back end. the inner cab corner has a rubber plug in it.
I prime with self etching primer and paint the insdie of them before putting them on. Then I blast as much paint as I can down inside them, top it with undercoating.