Neither FileMaker 13 advanced nor FileMaker 12 would be the Host. FileMaker Server (whether it be 12 or 13) should be the host. You should use the sharing button to upload your file to the server while Filemaker is launched but your file is not yet opened. For details on this, see: "Uploading files to FileMaker Server" in FileMaker help and consult the documentation that comes with FileMaker Server.
There will be no need to create runtime systems if you plan on hosting them over the network.
Since FileMaker 12 and 13 use the same file format, either server 12 or server 13 can host a file created by FileMaker 13 Advanced and both FileMaker 12 and 13 clients can use Open Remote to access the file. But FileMaker 13 specific features may not work if the file is hosted by Server 12 and will not work at all for FileMaker 12 clients. There is also a setting in FileOptions that may need to be changed before Filemaker 12 users can open the file as it can be set to prevent version 12 users from opening the file.
So that means in every open or login users to FM Data the method would be "Open Remote?"
What if I will add another client or another computer in a client and have not purchased filemaker pro (do not have Filemaker Software in this Computer) Can I use the runtime Solution to access the filemaker Server so It will be another client?
Yes, when a file is hosted over a network, only "open remote" should be used to select and open a FileMaker Database file.
A Runtime file can be hosted by Server but that's the same as putting the original copy of the file up on server so there's no advantage gained by doing so.
If runtime solution is hosted in a server that means not required of installing the filemaker pro? Can it be?
No, to access a database hosted on FMS, a FM client is needed (or FMGo on iOS or a browser via webdirect)
Runtime solutions are not 'networkable' - but can be hostd on a FMS, to be used like a 'normal' FM file
What is the different of FM client and FM pro? I there a FM client free if FM Server is purchased?
"client" is not the name of the software, it's a "role" that it can or (in the case of a run time application) cannot play.
The following applications can be a "client" of a hosted FileMaker Database:
FileMaker Pro Advanced (but this is only a good idea for the person developing the database. Other users gain no advantage from using this much more expensive version.)
A Web Browser such as Chrome or Internet Explorer (FireFox is not certified for this). This requires publishing your database to the web using FileMaker Server with WebDirect.
Thank You. Well we cannot aford to buy many FM pro so maybe we will start with stand alone database using the runtime. ;)
I'd research that option carefully in advance. Inability to share files over the network is not the only limitation of FileMaker Runtimes. You may also have problems "synching" your data if you plan on distributing multiple run time copies to different users and then merging the data back into a single copy.