SQL Server Management Studio - Actual Execution Plan - Actual Row Size and Actual Data Size
I can see the Estimate Row and Data Size, but where is their actual
  size? Is there a way to see this information?


As commented by @Randi Vertongen I use SQL Sentry Plan explorer to see actual data size if I need. This is a free tool you can download (without even giving out your email address).

Plan Explorer Installation &amp; Overview

Here is an example of that data you are looking for in plan explorer.



As far as actual number of rows and number of rows read is available in SSMS tool tip or properties. Here is an example.




  Same question for actual CPU, I/O, number of executions and so on.


For CPU and I/O you can right click individual operator and see it in properties or look at xml.  If you right click the leftmost node and see it's properties you will total use of total cpu and  memory grant details. Number of execution is also available in SSMS. See picture above.

Following is an example of overall cpu, time and memory grant information:

 

Following is an example of looking at details per operator. This will vary depending on the type of operator. This output is from a sort operator.



Here is a partial list of when some of these features were added and back ported to older versions.



Overall plan explorer is a far better tool to look at execution plan and many data professionals use it everyday.