Q: Does HotA have breakpoints?
A: Yes, see below. In general, they match up fairly closely with sprint/ww ones, and there are more available. Try to make sure that you are not barely below one when buffed with WotB. Other than that, don't stress over them too much.

Q: I want to use a DTWW/HotA hybrid with my Skorn. How much attack speed do I need?
A: Most of us advocate reaching the 17 tick breakpoint, which requires 1.67 APS when buffed with Wrath of the Berserker. With a non-IAS Skorn, this requires 42% IAS from gear. Nubtro suggests 43% in case you drop wrath of the berserker, as there is a breakpoint at 1.43 APS. With an 11% IAS Skorn, only 26% IAS from gear is necessary to reach the same breakpoint. The 18 tick breakpoint is significantly smoother. This requires 1.82 APS buffed, but it's recommended to also hit the 1.83 APS breakpoint for HotA if you're going this route. With a non-IAS Skorn, this requires 58% IAS from gear, or 7 slots. Don't attempt this without a very large budget. With an 11% IAS Skorn, this breakpoint requires 40% IAS from gear.

Q: Which rune of HotA should I use?
A: The most popular option is Smash due to its high proc coefficient and damage output. It synergizes well for dual wield barbs who use DTWW for their AoE damage. When relying on HotA for AoE damage, other runes can be preferable, as Smash reduces its effective area. Thunderstrike is my favorite, as it stuns mobs easily and consequently makes fury generation easy. Rolling thunder has a low proc coefficient, but has the highest area of effect. All 3 of these runes are worth consideration if you wish for HotA to be your primary source of damage.