Taking extreme positions doesn't win elections unfortunately. Trump has a few of his own extreme opinions and I feel relatively confident he's going to lose pretty bad to Hillary because of it. Hillary is the master of no extremes.
That really depends on where you're coming from, politically. Compared to some places in the world, the most "liberal" and "socialist" Democrat (no, not Hillary) is already a right wing extremist. For starters: She's a hawk. She and her husband deliberately came in to office to push the already right-leaning Democratic party further to the right. She's for enlarging the already massive surveillance state. These are not moderate positions to a lot of people. Maybe moderate compared to Trump.
Regarding whether a moderate or an extremist is more likely to win, there's little evidence that Presidential elections get decided on political positions. Sadly, personality and style are far more significant.
Of course, my preferred choice is Bernie, but with how plainly and obviously corrupt the DNC is, I don't have a lot of hope of him getting the Dem nomination and running in the general election. Maybe things will go totally haywire and both Bernie and Trump will get pissed and run as independents after the establishment railroads them both, and then we'll have a 4-way race.
If you removed gun control views Hillary could run just fine as a Republican. She's in favor of climate change policies too, which establishment Republicans disagree with, but I don't see many average joe Republicans giving a shit about it.
You are right though, she really has no extreme stances. This is mainly due to the fact she tailors her views and policies to what's popular at the time.
except for consistently lying...