I never heared of an external S/T combo. At least not in the country I live. The same thing counts for the 2 card slot. In the country I live there is only one provider, so I have no need for 2 cards. I have a Dreambox 500HD, performs very well, but that one might be over the top for you, as I use it for other purposes too.
Personally I would visit a satellite-shop, and try out different receivers and see which (graphical) interfaces you like. How fast is the zapping time. How many commands does it take to switch from tv -> radio and switch the backlights off. Things like that. Write down the boxes you like and verify if there is a match in the PUC-list for your TV. What other members here will recommend, doesn't have to be the best choice. Receivers these days, can be very small, consume less (heat) and perform better. Your own choice is the best.