Do they make one that will do 50 cent pieces?

Yes, they did, but I didn't order that one since I only had one half-dollar in my massive coin pile and it didn't seem cost effective to me. You don't run into too many of them in real life cash tills as they're not nearly as popular as they were back in the 80's and 90's when I was a kid. At this point in time, the Gold Sacajawaea One Dollar pieces from 2000 and the slightly octagonal shaped Susan B Anthonys from 1979 are more commonly circulated than the JFK half-dollar from 1964 onward. Although not by much.

How many coins fit in each tube?

The colored coin rolls that correspond with the sorting tubes will say how many fit in the tube. If you use the sorting tubes with the coin rolls, you never have to worry about overfilling the rolls as any excess coins, say beyond 40 for the orange colored quarter tubes will spill out the top of the sorting tube if you go beyond the pre set number for the coin type and roll in question. So generally, 50 for dimes and pennies (green and red), 40 for nickels and quarters (blue and orange), and I think 40 ($20.00) for the half-dollars (gray). I don't know with them as I didn't buy the deluxe sized kit that included them.