Is this product weatherproof to enable mounting under a caravan or does it need to be protected in a box?
The multiswitches are designed for indoor use, so yes, it would be better in a box.
which is vert in and horiz in
Both ports do either H or V or both. It makes no difference which way the cables go.
CAN U USE ANY OUT PORT 1-4 TO YOUR TV
Two ports for input from the dish (any cable from the twin LNB) and any port out to the decoder box then HDMI from the box to TV.