I think I know what you mean but to clarify:
In 2. what do you mean by “copy the link to the video” ? Copy the link to where?
in 3. what do you mean by “my playlist’?
in 4 .what do you mean by “navigate to my playlist” Where and how?

I do all this with WIIMC using the features of the enhancement pack. Search Navi, save desired streamlinks or playlistlinks to savedlinks.xml on the PC, then move those links to custom folders in onlinemedia.xml also on the PC, then restart WIIMC and play the links from OLM custom folder. Other option is to manually copy thevideo links on the PC to an .m3u playlist and open it in Video mode to play the links.

The ability to play in real time depends on the speed of your link and the attributes of the video. If the link is too slow or the video is too “bitty” the WIIMC will buffer. Sometimes I use the enhancement pack option to display the video attributes before proceeding to play. That way I can make a rational decision. If the video is an AVC it will probably not play smoothly because it is too “bitty” (ie: the WII is not powerful enough to decode the stream into all the bits it needs to play). The “online codec” will usually play smoothly up to a pixel width of 640, so I set the enhancement pack options for AVC and OnlineCodec width to 640 and always get a warning message if the video exceeds those widths.

The cache fill setting is always on. What do you mean by “help with the buffering” ? It always buffers. Buffering is only obvious when you are playing the bits faster than you can load them, which depends on the connection speed and the codec.

Yes that’s my understanding too, however my experience shows that if you can fill the buffer faster than you use it a big buffer will only delay the start of playback. You can see this if you “home” when when the buffering starts and then resume … the buffering delay will not come back.