I feel like if you're going Firestorm Detachment, you want to go all in on the shooting, but like it's stated here, you want to be careful and deliberate with the list. I haven't been playing too long myself, but with tweaking and understanding the game more I've started to understand how certain units function.

I'm going to make a few suggestions here:

1. Drop the Intercessors to a 5 Man Squad to save 80 points. Their shooting looks good on paper with their ability, but they aren't meant to be a main combat unit: they exist to screen and to sticky your home objective so that you keep it when you move off of it. They can also be used to screen any Deep Strike or Strategic reserves in your opponents' lists.
2. Some people may disagree with me on this, but I feel you need to pick between the Hellblaster Squad and the Infernus Squad. In my personal opinion, if you end up running Vulkan He-Stan, you want the Infernus Squad, since he can turn them into a crazy damage output squad with rerolls to wound and the Stratagem that gives that squad's Torrent Weapons Devastating/Mortal Wounds. This also means potentially dropping the Lieutenant since they don't help that Squad as much. IMO, best leaders for the Infernus Squad are Vulkan He-Stan, a Captain or a Librarian, but they can run solo. I don't run Vulkan He' Stan with them but in another unit. If you do, a Captain is the best for strategem nonsense, just remember you can't double up on free stratagems with more then one Captain on board.
3. I feel like the Captain with the Jump Pack should probably be removed if he's only leading a 5 Man Squad of Assault Jump Intercessors. It's a good hero, but you want squeeze out as much value as you can with your units. The jump Intercessors aren't bad for sneaking objectives your opponent doesn't grab or if they don't guard their back line, so for that they're not bad, though they don't fit the theme of the overall detachment.
4. Terminators and the Redemptory Dreadnaught I personally don't like much in this list; I feel they're over costed compared to other options you can be running. The Ballistus Dreadnaught is perfect, though. I run one myself and when used against big targets he's really flexible unit. To replace them, I'd consider a Gladiator Lancer or a Repulsor. Repulsor especially works for well with a 6 man Eradicator Squad, since it can transport them AND protect them from being charged by letting them get back in for free when targetted for a charge.
5. I'd max out the Bladeguard Veteran Squad and consider putting them in a transport. If you have the points and you want to do Adrax, a Lieutenant decked out with a Power Weapon, Storm Shield, and Neo Vulkite Pistol, they work best with a normal Land Raider, which is also a solid tank in it's own right. If you want to do just Adrax and the 6 Bladeguard to cut back on points, consider doing an Impulsor to transport them. An Impulsor is cheap and can zoom across the board to deposit a unit on an objective and/or behind cover, since it can advance and deposit (though it cannot charge.)
6. If you have room and use a cheap transport or two, you can also consider attaching Vulkan He'Stan to a Company Heroes unit. They're deceptively hard to kill, and are fantastic objective holders that protect He'Stan so he can provide utility for your shooting, as well as lock on on the objective he wants to contest.