Its included inside 1.70 or 1.71 builders resources in full 2da source folder, which defaut files you mean? I have no idea what are you talking about.
About installer - it contains all languages thats all. Otherwise there is the same content as in the manul distribution, new bif file in NWN/data (which by itself has no impact on game) and modified xp2patch.key file that tells game to load content from the new bif + altered texture pack with some texture changes.
As for your another question. I keep repeating it all the time and its written like in every page about CPP minimally twice...
Player with CPP will be able to join server without CPP. And Player without CPP will be able to join server with CPP. (Unless you specifically restrict that and allow to join only players with CPP which is possible to do via adding the patch17X.hak into your hak list)
As for builder, this is a bit tricky and probably hasnt been fully explained by me yet. So - by installing the patch on your local machine, you wont get module updated. I mean, you will but only if you host it from your local machine. CPP must be installed also on server (and since dedicated server has no default path installer doesnt work there you need to get manual version) to get this.
There are two notable exceptions or caveats:
1) if you as a builder install CPP and then you recompile all scripts in your module, since recompiling process works with your client files altered by CPP you get some of the CPP changes into your module regardless that server has CPP or not (because scripts are not recompiled on the fly unlike different programming languages).
2) viceversa, if you got CPP installed on server but not on your local machine and you recompile the scripts on your local machine then you will lose some of the CPP fixes/improvements (provided you recompiled scripts with CPP before). This is important to keep in mind if multiple builders can work and upload module on server. (For example on PW Arkhalia where is 1.71 installed after I left, another builder without CPP installed on his local machine recompiled all scripts in last module and then players noticed the creature AI get changed.