Yeah. The other option is pre/pro + amps, but that's relegated to the high end because it costs more than the combined HT Receiver. But these days you have to have something to process all the digital audio formats in use.
Depends. I use my Onkyo Receiver as a preamp. Then I purchased amps to use with it. I got the receiver for $350 from Onkyo refurbished. Since most Onkyo receivers fail due to heat issues, taking out using the amp section drastically reduces heat (my guess anyway).
I have an inuke amp (I do not recommend unless you're willing to do a fan mod and willing to take a risk on it failing)
and a CrownXLS1500 (I do recommend but they're more expensive)
To drive speakers + Subwoofer (Inuke amp drives rear speakers and subs. It's the NU4-6000).
It's not necessary though and most users will be fine with using a receiver with no external amplification. Just put your receiver ina well ventilated area, especially if it's an Onkyo lol.