I am building an app which has a number of listviews, for some phone it will be longer than its screen. So a global scroll bar are required. However, the listview has their own scrollbar bar, It will make scrolling some strange! Thus, I need to disable all scrollbar, only leaving the global bar.
There are no properties in ListView control to disable its scroll bars. The only way to do that is set HeightRequest to a super big number.
I wish in their future version can have this useful feature.

I am not an expert in Xamarin. I only have spent 6 months on this programming platform. Thus, please feel free to response this post.
My frist preference is to Shared Projects. That is easier to manage. I can share xmal files across each project. That is simple, I think that is good to use in a small and one-off project.
However, if you have more focus on reuse, I think you choose PCL. That is more like a standard control library. You can use the controls in the library easily! Also, you are building a larger scale project, I think that is safer to use PCL, because PCL is more self-contained.
I think using PCL or Shared Projects is depending your project scale and goals.

In Xamarin Form, you have to know how to use CustomRender. You need to use it to preform some platform specific functions. However, we need to access some properties from CustomRenderer to Xamarin Form Control, such as its height and width, That is very easy to do, you just need to use Element property.
e.g.

Code

Last night, I went to the .Net User Group in Brisbane. The speaker introduced the new product from Microsoft, Code. That is a visual studio style code editor. Well, that is not very impressive at all.
You are not right, that is an very interesting product. It can run in OSX,Linux and WIndows. It provides a tool to work on interface codes outside from Windows. It made my life easier, I can do all js and shtml in OSX and leave only a bit little c# code which I can do in visual studio in windows VM.
Although it is a code editor, it still has some debugging features, it can debug node and mono application.
Lastly, even you only require to use Windows, that is still good to try this. This is without all heavy weighted features from Visual Studio. It load up so quick and less chances to break! That is very cool to use!

Yesterday, I fired a Virtual Machine with Visual Studio 2015 RC. This is the best way to try out this. Unless you need to download the installation files and install them. I think it requires about an hour, firing a VM is only about 3 minutes.
I tried it for a little while, that is not bad at all. The major improvements are in mobile app development, it has a better integration with xamarin. However, you still need to download xamarin.