Battlegrounds requires the GM (only) to set up port forwarding if the GM is behind a router. Setting up port forwarding is pretty easy, and if you have a static IP address it only needs to be done once. Those who have no way of controlling port-forarding (e.g., hotel guests, or students in some college dorms) can use a free VPN program like Hamachi to get around this.
Battlegrounds automatically sends the players any media assets they need, including maps, tokens, portraits, visual aids, and short audio clips. Visual aids and audio clips that are larger than 2MB (uncompressed) will need to be distributed to the players prior to the game session. Battlegrounds lets the GM easily create a media bundle for all the media required for each Encounter. This allows content to be displayed immediately when needed in a session, without waiting for transfers to complete (the same is true of Battlegrounds' artpacks).
Battlegrounds' Fog of War system uses a combination of dynamic reveals (which are calculated automatically based on light sources present and any special night vision the characters possess) and manual reveals (the GM uses draw tools to reveal or conceal the areas they want). Battlegrounds does not have a line-of-sight-based Fog of War system like MapTools does.
Tech support can take any number of forms. Via forum is the norm, and email support is also very common. On occasion I've even done tech support via Skype, iChat screen-sharing (for Mac users), or via Battlegrounds' built-in chat Lobby.
Hope that answers your questions.