Have a SVN checkout location connected to Codeplex and propagate updates to another develpment location connected to another SVN repository

I would like to checkout a read only SVN projects (e.g. from Codeplex) to a folder on my local disk, open the solution (let's say I am getting Dotnetnuke and open it's solution, add some projects to the solution and possibly changing some files, previously making them writable. I want to regularly update the changes coming from Codeplex and do code mergers to preserver my changes).

However I would like to copy all the files in this checkout location to another "developer" location where I would play extensively with the source code and have my local SVN repository to preserve history and allow other developers to do check ins/outs. I should be able to use TortoiseSVN from Windows explorer or Visual Studio SVN Add-on to do check ins/outs.

So check outs from Codeplex to the first location would be an intermediate location from which I would like to update a development area in another location that will be connected to Read/Write SVN repository on my local machine.

So how to make updates/synchronizations between first and second location (direction is from first to second location). Can I use Tortoise SVN to move changes from first location to second (after SVN update from Codeplex).

Since I am using GIT and Mercurial clients how would I propagate changes to my Development SVN location. I would prefer solution that would work across source version software. Tx, Rad

You can use SVN switch to switch between repositories, although that could be tricky thing to do...

Wouldn't adding the Codeplex' repository as an external to your R/W repository do the thing? See: http://svnbook.red-bean.com/en/1.0/ch07s03.html