The "Read-only" bit is inconsequential to security. It's an arbitrary attribute bit that an application can choose to ignore (most do).
If you're having permissions problems writing a file, the pertinent info will be in the Security tab.
Windows permissions / ACLs are very reminiscent of those invented by Digital - which is what you might expect given the author of Windows NT.
UAC sees to it that your normal processes run as a non-privileged shadow of your user account, presumably to protect your system from the things you haphazardly do (I hate the assumption that I'm using my computer stupidly, as I'm sure you do). I guess
most Windows users blindly execute anything from the internet that promises them glitz and glamour.
UAC also "magically" redirects some file accesses to different places on your drive, presumably to help make older software "better behaved".
You'll need to determine the specific permissions settings for the files you're trying to write, and what their paths really are.
What well-behaved applications (that need to access things that are for whatever reason normally blocked by UAC and permissions) are expected to do is this:
1. Run their installers at an elevated privilege level (you set a flag to let Windows know you need this). The user will have to answer a UAC prompt during installation.
2. Access the things the application will need and specifically open up the permissions to allow the application ongoing unfettered access. This might involve granting the user Full Control permissions, for example.
Beyond this, if you're really just looking to operate your computer yourself, and you EXPECT to have administrative privileges 24/7, then you might want to consider killing off UAC entirely. The only downside to doing this is that Metro/Modern toy
apps won't run without it on. To shut off UAC is exactly like it was in early Vista releases, before Microsoft added the ability to disable it (which they've removed again): You have to change the EnableLUA value in the registry to 0.
Hope this helps.