Enhanced Cross Section Shader

Hi,

I need your help for building a cross section shader and have two different issues. I hope you can help me!
First of all: Although I have some experience with shaders in unity, I'm still a beginner.

Here is my basic (and working) cross section shader:

https://drive.google.com/file/d/0B5GmHCLEk27GSHFpNlRfWmpzQWM/view?usp=sharing

Spoiler

Code (CSharp):

1.  
2. Shader "Slice/Slice1"
3.     {
4.         Properties
5.         {
6.           _MainTex ("Texture", 2D) = "white" {}
7.           _section ("Section plane (x angle, y angle, z angle, w displacement)", vector) = (0,0,0,0.15)
8.         }
9.    
10.         SubShader
11.         {
12.           Tags { "RenderType" = "Opaque" "Queue"="Geometry" "IgnoreProjector"="True"}
13.           Cull Off
14.    
15.           CGPROGRAM
16.           #pragma surface surf Lambert
17.  
18.           struct Input
19.           {
20.               float2 uv_MainTex;
21.               float3 worldPos;
22.               float3 viewDir;
23.               float3 worldNormal;
24.           };
25.  
26.           sampler2D _MainTex;
27.           float4 _section;
28.      
29.           void surf (Input IN, inout SurfaceOutput o)
30.           {
31.             float toClip = _section.x * 0.1 * IN.worldPos.x +
32.                            _section.y * 0.1 * IN.worldPos.y +
33.                            _section.z * 0.1 * IN.worldPos.z +
34.                            _section.w;
35.                        
36.             clip( toClip);
37.          
38.             float fd = dot( IN.viewDir, IN.worldNormal);
39.  
40.             if (fd.x > 0)
41.             {
42.                 o.Albedo = tex2D (_MainTex, IN.uv_MainTex).rgb;
43.                 return;
44.             }
45.        
46.             o.Emission = tex2D (_MainTex, IN.uv_MainTex).rgb;
47.           }
48.           ENDCG
49.         }
50.         Fallback "Diffuse"
51.      }
52.  

My next step is to implement some normal map functionality.
I tried this:

Spoiler

Code (CSharp):

1.     Shader "Slice/Slice1"
2.     {
3.         Properties
4.         {
5.           _MainTex ("Texture", 2D) = "white" {}
6.           _BumpMap ("Bumpmap", 2D) = "bump" {}
7.           _section ("Section plane (x angle, y angle, z angle, w displacement)", vector) = (0,0,0,0.15)
8.         }
9.    
10.         SubShader
11.         {
12.           Tags { "RenderType" = "Opaque" "Queue"="Geometry" "IgnoreProjector"="True"}
13.           Cull Off
14.    
15.           CGPROGRAM
16.           #pragma surface surf Lambert
17.  
18.           struct Input
19.           {
20.               float2 uv_MainTex;
21.               float3 worldPos;
22.               float3 viewDir;
23.               float3 worldNormal;
24.           };
25.  
26.           sampler2D _MainTex;
27.           sampler2D _BumpMap;
28.           float4 _section;
29.      
30.           void surf (Input IN, inout SurfaceOutput o)
31.           {
32.             float toClip = _section.x * 0.1 * IN.worldPos.x +
33.                            _section.y * 0.1 * IN.worldPos.y +
34.                            _section.z * 0.1 * IN.worldPos.z +
35.                            _section.w;
36.                        
37.             clip( toClip);
38.          
39.             float fd = dot( IN.viewDir, IN.worldNormal);
40.  
41.             if (fd.x > 0)
42.             {
43.                 o.Albedo = tex2D (_MainTex, IN.uv_MainTex).rgb;
44.                 o.Normal = UnpackNormal (tex2D (_BumpMap, IN.uv_MainTex));
45.                 return;
46.             }
47.        
48.             o.Emission = tex2D (_MainTex, IN.uv_MainTex).rgb;
49.           }
50.           ENDCG
51.         }
52.         Fallback "Diffuse"
53.      }
54.  

But I get the following error: "... Too many texture interpolators would be used for ForwardBase pass at line..."

I also tried to add " #pragma target 3.0 ", but then I get another error which doesn't really tell me where the problem is : " ... invalid subscript 'TtoW0' at line 145 ..."

What is the problem there?

My next problem is, that I want to cap the holes.
My idea is using Stencil Buffers and create a mask from the Back and Front Cull to get a mask from the "seams" and finally take a plane and control its visibilty by the mask I have created...
But the problem I have is, that I don't even know how to get started...
Does someone has an idea?

big thanks to you in advance!