Since my corvette is in the shop as it were getting "engine upgrades", I thought I'd take a little time to do some zen strategizing and ask what approach I should take to defending the ship in battle.

I know I probably should protect the aft section, so I was thinking about forming up a fighter screen of Y-wings and/or HWKs (turrets) and then have a second screen of X-wings or B-wings, as well as a couple of A-wings for and early alpha strike, but obviously I haven't done much with it yet so I don't know the points I'll have to play with or what I'll be up against.

I'm assuming the enemy will likely bring TIE Bombers and HLC-mounted Firesprays to the table, and TIE Interceptors because of their high agility and three attack dice.

So, got any advice?

You already posted what I was going to suggest. I would be sure to not venture to far from the ship and unless you are zooming A-Wings, I would not get in front of the ship. Be ready to push forward and smash your enemies when they let there guard down...if they do get close.

You should stay on your Capitol Ship's flanks like glue. It is their job to strike approaching enemies, not go chasing after them.

Hwks with blaster turrets, coms booster and quad lasers...

This lets you pump your hwks with focus even if they are stressed or blocked.

B-Wings with ion cannons have been good for me. They can make them drift into your path and get run over. Plus the 2 k-turn is nice when you need to turn and shoot things that got behind the corvette

I've had the CR90 in two games, one at 230 Points on a 3x3, and one at 300 that was a 2v1 team game on about 4.5x3 (a friend's kitchen table). I believe both times we ran without asteroids since they were first time Corvette users (myself in the first case, and a friend borrowing it in the second). Both games were against an equivalent (points-wise) number of Imperials. From what I've seen the Corvette can more than pull its weight, as it took out all except 1-2 ships from the first game, three by running them over, and in the second game, it played more of a long-range fire-support role, as my fighters were quite nasty on their own, and bore the brunt of our opponent's attack.

I will add, however, that my opponents lacked a large quantity of Large Based ships, as my first opponent had none, and while the latter had a Firespray (sans HLC) and Lambda, they were priority targets for me and did not last very long. Special credit to Dutyfree for stressing the Lambda and then running it over, and then taking no damage from the rolls.

I would suggest bringing along a Transport kitted out for disruption and support (Toryn Farr + Dutyfree Title), and a few tricked out fighters for escorts. As far as strategy, in both games I played, the Corvette advanced slowly along a board edge for several turns, building up energy, before turning to engage on the enemies. To that end, I definitely recommend taking a Single Turbolaser for at least one of your Hardpoints, so you can have at least two attacks out to range 5 in a turn. I'm not sure if I'd bring any more than that though.

As an aside, Ionization Reactor is great upgrade for any ships that get too close, and they can set up enemy fighters to be squished on the following turn, but be careful you don't get your own ships with it. Tibanna Gas supplies are your friend, and Reinforce Actions save lives.

However, if you feel like there isn't enough "Boom" for your list by taking a GR75 in addition to the Corvette, then roughly 150 points of fighters would likely do it, and it wouldn't hurt to bring a HWK with them either.

Just my two cents.

I tried a 300 pt game using a Corvette with Quad Lasers and a Rebel Transport with a fair amount of upgrades. I also had 5 other Rebel ships light on upgrades. The Imperials had 3 bombers, a shuttle and 3 firesprays, all heavy on upgrades, IIRC.

After asteroid placement, my opponent placed his bombers at one corner, so I immediately placed my Corvette and Transport at the other corner. The bulk of the rest of my starfighters started next to the huge ships on the bombers side.

Things got bunched up in the center as the firesprays, shuttle and bombers were working their way toward my huge ships, so the transport barreled through and killed 4 of them over 3 turns. The Corvette completely broadsided one of the firesprays. What remained was 2 Rebel starfighters and the Corvette against 2 bombers when all was done.

The Corvette had a surplus of energy. I kept forgetting to spend an extra energy to roll 5 attack dice.

In the end, I realized I probably don't want to think too hard about how to defend my huge ships. Having escorts that can fly beside or fly out and intercept are probably the most useful, but a focused intercept strike force also has its merits.