This forum has some great threads on Internet and connectivity issues. For a good introduction try:
RV Mobile Internet Resource Center - WiFi, Cellular, Satellite | Technomadia
Also look for threads on how people are mounting and transporting TVs, especially if you want a larger one.
You will want to have ETI run the power and other cables you need during the build, even if you decide to buy parts of your system somewhere else. For example, if you want a satellite dish, how is the signal going to get to the box? Do you want a cable coming from a roof mounted antenna or through the wall from a tripod mounted one? Think through all parts of your systems and plan where everything will go and how it will get the power and signal it needs. Also check with ETI and make sure wherever you plan to mount your TV is strong enough and get it reinforced during the build if necessary.