You could easily sort the conversations by the parties involved. This should solve any conversational confusion. As for programming knowledge, I would encourage JavaScript. It's what I'm currently learning and it would be very capable to execute a project such as this.
You are envisioning the option to add a pictorial element, almost like achieving a vid podcast quality to the vox?
Now that I think about it, this would complicate things. I think I would ultimately settle for plain color backgrounds for the tiles. The array of tiles (I'll throw together a sketch of what I'm envisioning soon) would simply allow for a colorful, more unique browsing experience compared to an ugly wall of text.
if we were to use imgr/soundcloud. But free usage of these has severe data limitations.
I could pay for a VPS server if needed. I would much rather control my own data than a third party controlling it.