You can make group assignments by selecting however many ships you want in it and pressing "ctr + number". The numbers then let you quick select the groups (including in deployment!). I like to use this for making my carriers a group and setting a rally point for them with right click. I will often do this a ways behind the rally point(s) for my main fleet (for a large fleet of my own I'll put 2 defend orders and 1 carrier rally order in an inverted triangle. Works well at keeping things grouped.
In your case you could assign each balanced squad to its own group, then assign each group to its own rally point. Be aware though that if the group gets swarmed, it will probably separate out into its individual members. Pretty much as a rule carriers, missile ships, and long ranged support does best when there are some frontline "brawling" ships to soak up the enemy attention.
For escorts: I usually find that frigates makes poor escorts because they rely on movement to get out of trouble, and escorts are chained to the flag ship. Its really easy for a frigate escorting a cruiser or battleship to die. However, I've found that destroyers, especially tough ones, make good escorts: the best use of Enforcers that I've found is as carrier or cruiser escorts. They stink as independent ships but are nice flak/missile support platforms, and are so slow that they won't run ahead of their assignment. For battleships, cruisers or even another battleship make for good partners.
For the eliminate command: This will make the assigned ships "go for it"... so its really important to both be careful in making the assignment, and also in removing the assignment. The AI likes to retreat its fluxed up/damaged ships behind fresh allies (as I'm sure you've noticed) - at that point I usually remove the eliminate command as a failed order.
Eliminate can be really useful when you notice an enemy that has fallen out of formation, or when there is a matchup going on that you know your ship can win if it would only get over itself and shoot. About half the eliminate commands I use are against enemy frigates to get my own frigates to fight - the other half are on stragglers and/or flimsy carriers.
Avoid is very powerful in keeping your ships out of trouble from a killer enemy, but as you've noticed its got a really wide radius. I will use avoids on an enemy cap while my fleet takes out escorts. Typically I will engage the ship myself in something mobile like a destroyer to draw its fire and push up its flux, then flip the "avoid" to "eliminate". With a bit of luck the capital will be out of flux and out of position for the ensuing strikes.