You get your slaves to aim/face they way you want to aim/face you will have to move so that they look that way. or you could use repeater broadcast and turn like that.

For wyvern sting you could set it where you have a button that in wow /focus your current target. then in isboxer you could make it a round robin when each time your hit that button only one toon does /focus on your current target. Then you could switch to next target and hit it again to /focus with another hunter and so on. Finally you would have a button for wyvern sting and a macro that would be like /castseqequence [target=focus] wyvern sting. Or more simply you could have wyvern sting set up on a round robin and just go from target to target casting wyvern one at a time.

In the case of hunters i would stretch to say their play style may be similar to my ele shamans. So how i have it set up is all the buttons are exactly the same on all my bars on each toon. So like 1 is earth shock, 2 is lighting bolt, 3 is flame shock, and so on. SO it gives me the ability to cast specific spells whenever i want and they will all go through all the same to my slaves. However, I also have macros set up in wow that automatically cast spells in order and stuff.

Example.
/castsequence reset=0.3 0,0,0,0,Lava Burst
/castsequence reset=0.3 0,0,0,Lava Burst
/castsequence reset=0.3 0,0,Lava Burst
/castsequence reset=0.3 0,Elemental Blast
/castsequence reset=5 Lightning Bolt,Lightning Bolt,Lightning Bolt,Lightning Bolt,Lightning Bolt,Lightning Bolt,Lightning Bolt
/targetenemy [noharm][dead]

SO basically this is my lazy spam macro. Casts lava burst, elemental blast, and lightning bolt. I could see a hunter setting one up with Arcane shot, cobra shot and so on. But basically wht im trying to show is you can play it either where you hit one button and it does one thing like arcane shot, or you can set it up where one button hits multiple things.

Melee vs ranged. Well alot of that comes down to personally preference and which class you enjoy. I have a team of 10 dks and a team of 10 ele shamans. I like them both alot. I tend to find melee easier for me because unlike the shamans, when someone runs up in my face and is running around me i can just keep attacking because my dks are chasing after them. But with the shamans you run into the problem of facing and what not. The big downfall ive found in melee is often times with all the movement and interacting my dks do they tend to run off and get stuck in corners and on objects where as with the shamans i can be confident most of the time that theyre right behind me. Ultimately i would say theyre both pretty similar in difficulty of setting up. Id assume after running a certain team long enough one would be able to identify weaknesses and find ways around them. I could see melee being a little more difficult in pve because some boss mechanics prequire you not to stand in stuff and be behind the target which is kinda hard when your toons are interacting and running circles around the boss.

Get isboxer and start trying things out. Cant really see what you having trouble with till you finally experience it