I'm not an absolute beginner. I just learned in the 80's through mid 90's and haven't adapted my strokes for the modern game i.e. tons of topspin. My two handed backhand is serviceable, but has never felt comfortable.
When I had a 2hbh, the biggest source of discomfort and feeling of restriction came from me not shifting my weight enough before the forward swing. So if you end up sticking with the 2hbh, make sure you're stepping in at the start of your forward swing.
Also, if you alternate between trying a 2hbh and a 1hbh, a huge difference in the feel will come from the direction your chin/eyes will be looking in relation to your chest.
1hbh, you're looking either straight ahead or to your right (assuming you're right handed). 2hbh, you're looking
left across your body since your are opening up your chest more on that shot.
My one handed backhand is, again, something that feels more natural and that I think can be decent with some consistent hard work. That being said I'm only 5' 9" and the one handed backhand is definitely a little tougher on the higher balls, hence really wanting to learn a stroke that is going to allow me to hit with a greater margin of error.
What kind of grip do you use? Where is the index base knuckle, and where is your heel pad?
A grip correction is probably the easiest way to improve a flawed stroke.
I also find opening up the chest helps on high balls.
I notice from watching videos of Federer's backhand that he seems to drive through the ball a little more while just naturally supinating his forearm.
As Lee said, do not use Fed as a model unless you are willing to wait years for the payoff (which may never come). Fed spent his junior years developing that shot. When he was 16, he had a much more "stiff" backhand, which shows that his current bh was a product of years of gradual change based on simple fundamentals.
I think Wawrinka and Henin are good models, especially for a 5'9" person who wants to hit high balls better.
Is it a common misconception that massive topspin is used for every shot in tennis nowadays?
Depends what you mean by massive. Nadal-like, no way.
I'm guessing the topspin devils you'll meet will be landing most their shots in the middle of the court, and you can honorably wait for the ball to come down and still have good court position.
In any case, if you're worried about dealing with spin or moonballs, I recommend a strong grip, an early straight arm, and opening up the chest, and using the aforementioned models.