System recon is best performed by fighters: fast, cheap, expendable, numerous. They can cover more ground at lower cost. When there's reason to believe they may encounter opposition, they can be backed up at a discreet distance by a frigate with orders to engage if the fighters find something beyond their power but within the frigate's power, and to withdraw if the fighters encounter something too big for the frigate. Fighters have the advantage that if seriously overmatched they can scatter, assuring that most get back.
You assume poor control of your borders. If you have good control of your borders - i.e. resources positioned to keep you informed of any penetration of your space and its scope and movement - then you may want battlefleets strategically located to intercept those attackers before they reach your Coruscant-like systems. The layout of the systems may not give you a choice, but if you have the opportunity to defend forward, you should. Strikes me that huddling around the fortress worlds is surrendering too much initiative to the enemy and encourages your rocks to change sides.
This is more effectively done by frigates, who are more than a match for converted merchant ships and, since you can buy several of them for the price of a cruiser, can cover more ground. As with frigates backing up fighter, you can have cruisers back a bit and positioned to back up the frigates if they come back with reports of a marauder too big for them to handle. In that role and from those positions, the cruisers can also threaten the supply lines of an invading fleet, obliging him to disperse assets to chase them off and secure his lines.
Term not recognized. I presume this is a T5 thing?
Depends on the combat system. In High Guard, speed is life. In a combat system where speed matters less - well, speed matters less.
As to jump range, it depends on the nature of your escort. If they are intended to follow the merchant to the next system, then jump range will likely be no more than that of the merchants and more space can be allocated to offense and defense. If your defensive strategy is to escort them to the jump point and then have fast escorts in the receiving system ready to race to join them before a potential attacker can reach them, then you might rely on the more potent SDBs delivered to worlds with inadequate defenses by tenders.
Alternately, it may be useful to use the same design of frigate in both the patrol/raider and escort roles, so that assets can be shifted more easily if combat losses or a change in strategy require more emphasis on one role than the other.
There are key worlds; your reserves are stationed there, ready to move forward once you are certain of the enemy's axis of attack.
There are, or may be, strategic systems that cover the approaches to these worlds; your stopping forces are stationed there.
There are, or may be supporting systems where positioning strong secondary assets will force the invader to disperse his assets to secure his lines of supply.
There are the borders and surroundings, where your primary role is to detect and monitor enemy movements, communicate those movements to your command, and respond with assets appropriate to the scale of the threat without weakening your primary defensive positions.
Again, I'm not familiar with the abbreviation.
Depends on where the rock is. If the system happens to be a fuel-bridge through a region of otherwise empty space and planets lacking water or gas giants, they might care quite a bit.
