MorganB, in the right hands the Anubis is a much more powerful fighter than the other class 6ers. It is just not as easy to use as the more agile Barracuda or light fighters like Hawk and Drawk, and it requires a bit different tactics to utilize its advantages and avoid the drawbacks of its one disadvantage (lack of agility). By the way, the manoeuvrability of the Anubis is normal for a heavy fighter - exactly the same as Crusader, Dragon, Stiletto and Valkyrie, for example.
But the tactic for the final missions is pretty much the same for all ships: keep firing all weapons at the designated targets whenever there is a firing solution (remember that missiles and torpedoes have greater range than guns, mines drastically less) but keep moving
at all times (dodging/weaving a bit if necessary) unless you find that there is a lull in enemy fire; in the latter case you can use the X key (brake and reverse) to extend the time your ship is the quiet spot, until you get found by a squad of enemy fighters. If you stay close to a target then Alpha wing (whose leader you are) will help you destroy it, and the target will shield you from enemies in one half of the sky. Enemies shooting at you from the other half of the sky will likely hit the target instead of you, and with their powerful guns they are a big help in dispatching the targets.
As for combat against fighters: to get the most out of heavy fighters and freighters you need to use different tactics than in a light fighter, especially regarding which enemy you pick next. Using the R key to pick the nearest enemy is rarely a good choice - it will usually select the bogie that is 50 m behind you. It takes a lot of time to turn a heavy fighter or freighter around (during which time you get fired on quite a bit) and if you finally have the enemy in your firing cone you are too close to use torpedoes and missiles, both because the remaining time is too short to remove the enemy shield and because you have to get your ship to top afterburn speed in order to achieve maximum damage with explosive ammo. So, instead pick one of the enemies that are already in your forward firing cone, preferrably one that is in just the right distance for a torpedo/missile run. It takes quite a bit of practice to judge the tactical situation and to have a feel for whether a torpedo/missile can work in a given constellation, but it is more fun and more rewarding than using a light fighter to whittle down the enemies slowly but surely.