This fleet is not legal. Firstly, since the restriction citing that Demiurg Commerce Vessels have to outnumber non-Demiurg cruisers is in the cruiser section then it might apply strictly to the options available in the cruiser section. So you'd need to have more Bastions/Citadels than non-Bastion/Citadel cruisers. To be honest, since this is a Demiurg list, this seems to be probable. However, apart from that, you'd need 4 cruisers to field 2 Strongholds. Also, 1600 pts is a really odd size game to be playing. Just saying.
Having said all that, I'll advise as best I can. For a start, you'll want your Strongholds to be taking the brunt of the enemy fire, so play them forward. The Bastion is overpriced and can be easy VPs for the opponent, so don't expose it. The Protectors are really quite fragile so you don't want to expose these ships. Given they've got 90° turns and can bring all their fire to bear in the one arc they don't need to be positioned in the middle of the enemy, so they can safely be positioned as half-back flankers.
The Xenos vessels really are overpriced. They're pretty much a Firestorm and Firestorms are overpriced (being worth no more than 35 pts). You get some range, but this is pretty rubbish since it only applies to 40% of the weaponry and even then this is reduced due to the column shift for range. So the only real bonus over a Firestorm is the extra shield. Therefore to make the ship at all worthwhile you have to take advantage of this. That means you have to force your opponent to shoot at them. So use them aggressively, get up close and personal and punish the opponent for not shooting at them by liberal use of LO.
Since the lances only fire to the fore arc this typically will mean some increased return fire (as per the Firestorm), which is fine since you've got the extra shields. However, it also means that there's the possibility that the enemy will be able to manoeuvre out of your fore arc to then ignore your escorts (since you'll have to turn to fire you'll not be locking on). This means that he'll be free to take out your Protectors. I know that's what I would do. I would send in some attack craft to knock out a couple and then manoeuvre to avoid LO. This way I wouldn't waste any direct fire on them and simply whittle them away with AC.
I would probably recommend the targeting system on the Xenos escorts for this fleet. This is because you really want your opponent shooting at your Strongholds and to a lesser extent your Bastion so as to power up the prow cutting beam (and because the Strongholds can take a fair bit). This upgrade would allow your Protectors to take one flank and your escorts the other. It frees your escorts to manoeuvre as you choose, since the enemy will count as closing regardless of whether they're abeam or even moving away. This way you use your Demiurg ships aggressively, put them in the middle of the fleet to maximise their fire and bring up the rest for targets of opportunity.
Note: doing this makes the escorts much more attractive targets to the enemy, so they'll be more likely to target them instead of the Protectors. This does protect your fragile capital ships a bit better but the Xenos vessels will not be tough to direct fire of course. In which case I'd suggest liberal use of BFI for them. You want to keep them alive till you can get them on the enemy's six.
