Some tactical considerations:
1) Consider what upgrades like the Fire Warrior Shas'ui or Broadside Shas'vre get you. If you need them, great, but if not, they're easy places to shave points. Remember that the FW Shas'ui costs more than two Shas'la, and drones are also more expensive than more Fire Warriors. With an Ethereal around, you don't need the Leadership benefit, and the hope is to avoid assault altogether, so you don't really need the ability to accept challenges. In a Crisis squad, taking a Shas'vre might be more useful.
2) Consider what your opponent could bring, and how you'd counter it. In particular, consider the following threat models:
2a) Blobs of GEQ (T3/Sv 5+ or 6+) like IG squads, Eldar guardians, Kroot or Tyranid Gaunts.
2b) MEQ units (T4 or sometimes T3 or T5, Sv 3+) like Space Marines or Sisters and some Eldar aspect warriors
2c) TEQ (T4/T5, Sv 2+) like Terminators
2d) Light armor - AV10/11 like War Walkers, Piranhas, etc
2e) Medium armor - AV12 like Devilfish, Wave Serpents, Chimeras
2f) Heavy armor - AV13/14 like Leman Russ, Skyray, Ghost Ark
2g) Very heavy armor - AV14 all around. Land Raider, Monolith
2h) Monstrous creatures - these are varied, but in general expect T6, Sv 3+, W4+ and some mean abilities. T8 is not unheard of (Eldar Wraithlord/Wraithknight, Daemons with Iron Arm).
2i) Flying vehicles - light armor, can be one-hit-killed, but ignore low-strength outright and can't be grounded.
2j) Flying monstrous creatures - Can be grounded, have a toughness value, can't be one-shotted without ID weapons. (Some have T5, but S10 skyfire is rare)
In your list I see relatively few counters for TEQ and heavy/very heavy armor, especially if they have both. A squad of TEQs in a Land Raider could be seriously scary unless Longstrike gets lucky - you might have to risk dropping Ordnance ion blasts from the Riptides in places where they could scatter onto your gunline. Against monstrous creatures, you don't have much besides volume of fire. If the creature comes within range of your Broadsides and HBC Riptide, you can tear it up, but lists that bring a lot, like Chaos Daemons or Tyranids, could pose a problem.
Also, your Fire Warriors have fairly limited mobility for reaching objectives. You can screen them with the Hammerhead and Riptides, but as it stands, you mostly have to demolish enemy scoring units while mostly worrying about holding your backfield objectives. If there aren't enough to win that way, you'll have to get tricky. Having some outflanking Kroot could help, so could mounting one or two of those squads in a Devilfish.
You could put both the MSSS and the SI on the commander - remember that signature systems don't count as Crisis suit wargear slot items on a commander. You might also take Vectored Retro-Thrusters so he and his unit are harder to tarpit in assault, and maybe a twin-linked flamer for Overwatch. In my experience that kind of support commander works very
well with an HBC Riptide.
Now, as for allies: there's an article posted here about Space Marines as allies, and they clearly work well. (They're Space Marines. While not the top codex anymore, how could they be anything but effective, given the setting and the fandom and GW?) Farsight Enclaves is basically more of the same, but importantly it lets you take Crisis suits as scoring troop units. You can also access the excellent Earth Caste Pilot Array for one of your Riptides, too.
My favorite allies would be Eldar. The Farseer is an outstanding HQ unit that gives you access to the Runes of Fate and Divination psychic disciplines, which are excellent. Telepathy is solid, too. They have Windrider Jetbikes as scoring troops - these are awesome, and for the cost nobody beats 'em. They have an MEQ statline, can move 12", can JSJ, and have Jink. What's not to like? Eldar have some other really nice units too: the Fire Prism tank or its close kin the Falcon, Fire Dragons, Wraithguard, Rangers, Swooping Hawks. Finally, don't forget the unit that will draw an opponent's attention like no other: the Wraithknight. It's *huge*, towering over even a Riptide, and its T8/W6 statline with two guns that insta-kill on a 6 tend to draw the attention of most every gun that can hurt it. It's the ultimate incarnation of the Distraction Carnifex tactic outside Escalation/Apoc/Imperial Knights, and it's also rather effective in melee. (Four attacks at good initiative, 5+HoW on the charge, all S10 AP2? Yes please.) Oh, and I wouldn't exactly give an Imperial Knight amazing odds head-to-head against a Wraithknight. Certainly not with three Riptides backing it up