Combat works the same for NPCs and for PCs where skills/armour/weapons are concerned, so just think of them each as a squishier you that can die.
Ideally you'll want NPCs with high dexterity so they can hit (and weapon skill for a little more hit if they are still missing), dodge so they can avoid getting hit, and strength for HP.
If you are certain you can keep them out of enemy range you don't need to worry much about dodge/strength right away and can just dump the points into their ability to hit. Armour won't matter either if you're paying attention to enemy range, but if your goal is to keep them out of the line of fire altogether, you're better off targeting creature squads since they have more consistent ranges, whereas bandits tend to cover a broad spread.
As to race, anything that has good skills and race multiplier. Hutts, Noghri, Abyssins, and Togorians are popular choices, but there are many races with some good skills and decent RM so you have a wide selection.
If you plan to hunt on the same couple squares, it's a good idea to drop scout NPCs with perception skill, macrobinocs, and a sensor pack at a few points across the square (the number you need to reveal the entire square depends on the skills involved, but people use anywhere from 3-8).
If you have a sensor pack equipped you can share sensors with them and see the entire square at all times so you don't need to fly all over the square manually to check for spawns within your ship sensor range. If you don't have a sensor pack equipped, you can still share sensors while on board your ship, which is my preference so I can use my utility slots for more medkits and since I find you don't really need to see the whole square unless you're on your ship anyway.
It's not necessary but it sure makes life considerably easier if you're planning to spend much time hunting. If you're going to be moving around a lot between different planets or more than a handful of squares there'd be little point, though.
You do not have to use utility slots for medkits, those work fine from backpack/belt. Also, if you are short on sensor packs and macrobinoculars, you can use those cheap NPC shop droids as scouts. You'll need 25 K-4 Security Droids to fully cover square.
Yes, they can be used from inside of containers, as well as from the ground.
However, if you are using medkits from inside of containers, you have an additional page load to open the container.
That can be ridiculously annoying if it's inside of a container with hundreds of other items, or if you're on a slow connection (my phone connection currently maxes out at approximately the speed of a 56k connection). That's why I personally prefer using both utility slots for medkits as I don't need to refill any medkits or open containers while I'm at work. It's all personal preference.
Squad that is with you is called party and will earn XP while hunting the same way you do. As for patrolling, you can command your infantry skill +1 squad to patrol through your party interface. Thay will get XP each time thay move from one point of patrol to another. But thay will not move constantly, there will be random time delays at each point of patrol. When that delay is over, thay will continue to patrol.
Lets try again. Thay can, on Derra, where we have combat beta TESTING. So, outside of Derra, it is not implemented. Yet. One day, it will be. And no, you will not get exact answer when it will happen. It mostly depends on how much time developers can devote/steal from RL to develope game.