How can I display any standard write in visual mode.
For example if I run dc command it runs the program normally and displays all the text normally. But if I enter visual mode with V< enter > and use S to run through the program it displays the output maybe a 1/10th of a second: 
Can I have it display it for longer, or enter a command and see what has been printed to stdout so far?
I'm afraid there's no straight way to do so. You'll need to use rarun2 or radare's dd command.
I prefer the rarun2 way, it is more flexible and simple.
From man rarun2 output:
Debugging a program redirecting io to another terminal ## open a new terminal and type 'tty' to get $ tty ; clear ; sleep 999999 /dev/ttyS010 ## in another terminal run r2 $ r2 -e dbg.profile=foo.rr2 -d ls ## or you can use -R option $ r2 -R foo.rr2 -d ls $ cat foo.rr2 #!/usr/bin/rarun2 stdio=/dev/ttys010 For a step-by-step guide and more detailed answer, check my answer to a similar question here.
dd can be used to change file descriptors at runtime:
[0x00000000]> dd? |Usage: dd Descriptors commands | dd List file descriptors | dd <file> Open and map that file into the UI | dd-<fd> Close stdout fd | dd* List file descriptors (in radare commands) | dds <fd> <off> Seek given fd) | ddd <fd1> <fd2> Dup2 from fd1 to fd2 | ddr <fd> <size> Read N bytes from fd | ddw <fd> <hexpairs> Write N bytes to fd 