Best answer as chosen by user BobbyS1957: No.

1. Will any brand of adaptor work?
a. The makers.

2. Or do I have to buy the one made by Panasonic?
a. If you want their support to make it work? Yes.

3. My pref is to by a "mini" that does not stick out the side of the TV such as Belkin or Netgear.
Also, what is the "slowest" model I should buy?
a. The seller should help you here. But let me part with a non-stick device I use on my TV. Link follows
Bob

-> http://www.amazon.com/NETGEAR-WNCE2001-Universal-Internet-Adapter/dp/B007CO5DZ4/

I like this one since I can power it off some USB port on my TV.