You can use server manager, if you want. You just have to specify a path to the source file (just like you do with dism or add-windowsfeature) because the bits aren't stored on the local machine. That was a design decision, not a bug...
There is an update for Win7/2008 R2 that should allow alot of the Win8 performance enhancements to be available in Win7/2008 R2 (specifically file transfers and TCP/SMB optimization). I haven't done much testing with it yet, but it is on all of my terminal servers. Unfortunately, my terminal servers don't talk to 2012 servers yet, so I don't really have much to test with.
Yeah the .net 3.5 is an anoyance for me rather then anything else. It was a poor design decision imho since bulk of stuff still needs 3.5.
Thanks for the rollup I will check that out.