That seems like a solid list. Almost all of those troops are fairly popular Haqq choices.

For your first point Muyibs are really popular in lists people post on the official forums (especially as a link team), but they're usually described as a more advanced unit. They have great stats for a LI, and they come with lots of weapons in their loadout. That gives them a lot of tactical flexibility, but they're still just LI and not very sturdy with just one WND and almost no armor. Putting all those weapons to good use without getting yourself killed in the process takes some practice, but I like 'em they're cool models and you're right that mines have a lot of potential. Don't rule out the Hunzakut though. He would actually be even more useful in a Hacker list like you have here with the Barid than he has been to you up till now. All the Hunzakut loadouts come with a Deployable Repeater and with his camo and infiltration that Hunzakut is great at getting them into place. I do agree with you though that as a pure sniper Haqq has better choices. The Lasiq being the obvious choice, but the Tuareg is also up there being the only TO Camo unit in our army.

As to point number two, no it's not a big deal. You could ditch the doctor and get a ghulam with a Panzerfaust if you wanted to spend it but it's not necessary you've got plenty of offensive threats in that list.

Number 3. I haven't used remotes a lot for the very reasons you listed. That may change now with the Barid. We've got a nice Hacker/FO choice that can even be a Lt. I see him in a lot of lists and that opens up REMs. The total reaction remote is good at area denial but it's not super powerful. There are counters to it not the least of which is just shooting it with your HMGs. Chances are you'll have a better BS than the remote and more defense. It's a unit that will force your opponent to spend orders to deal with it though and sometimes that's more important than getting kills. The E/M grenade launcher is a little superfluous. There's just not many situations where you're going to want to shoot one DAM 13 grenade instead of four DAM 15 HMG rounds, but it could happen. Also getting the remote box will give you two remotes so you can make either the GML bot or the Sensor bot as well.

The engy is basically the doctor for mechanical units. So any remotes you're fielding he can put back on their feet. You also need an engy if your opponent is running an ADHL launcher and you want to unglue your guys. In the list you posted here you probably don't need one. They're a big deal in Paradisio Campaign missions though. You will want one for some of those if you ever play them. That goes for all the specialist troop types (Hackers, Doctors, FO, Chain of Command, etc.) but especially Hackers and Engy's. If you get one get the Kaplan engy he's just so much better than the other choice we have it's sad. If we're mentioning other models worth considering the primary of those should be our TAG. It's not the fanciest of TAGs but it's no slouch and it will really change up how your list plays. Having the TAG in your collection will give you some variety of list types with minimal model investment. The TO camo Tuareg model I mentioned earlier is another one that's nice to have though for different reasons. That one can help keep your opponent guessing as to whether or not you're going to AD drop on him. Just sub it out from time to time for the Ragik. Both TO camo and the AD units work well with Hafza lists so you can hide your deployed points, but you already mentioned picking up some of those.