The 75e is a bit undersized but will still work for FTA..You will miss many signals with that dish but if you are going to park it on a sat that has very few feeds but alot of programming then Galaxy 19 would be just fine for that dish.
The factory lnb is a Japan Radio lnb and they are actually very good performers.Myself I would not change out the factory lnb...What you will need is a multiswitch and it can be a powered multiswitch or non powered..I prefer powered multiswitches here to power the lnb`s but it is not needed!..The Horizontal output of lnb to the 18v input and the Vertical output of the lnb to the 13v input of the multiswitch...From there you can go straight to the receiver or if you would like to start yourself a dish farm then all is needed is the output of your multiswitch to a Diseqc switch
Welcome to the FTA world and Sat Guys.