In all honesty, he's right - largely ignore flyers. For the most part they struggle to do massive damage to ground targets anyway, especialy since the new rules prevented Dark Eldar and Ork fighter ripple-firing off all their missiles in one turn.
I've been playing a swarm infantry list myself, and my usual response to flyers is "yes, and?" - ignoring the aggravating little gnats has done fairly well so far.
I Wholehearterdly support lootas - they're awesome and massed BS2 fire means you needn't be too scared of snap firing - meaning going to ground, moving and firing or shooting at flyers works surprisngly well. The four flyers I'd make a priority target, given your list, are the Valkyrie (rarely seen in favour of its lascannon-toting sister the Vendetta, though), the Vulture, the Nightfire Launcher-armed Phoenix, and the Baleflamer-armed Helldrake. All of the above can do unspeakable things to horde armies. Anything else is an irritation at worst.
I would advise shoota boyz vs Sluggas. Since you can't run then charge, you always get to fire, and you can pre-measure at any time if concerned about killing guys in charge range, so you might as well take them. They put out scary amounts of shooting - and scarier amounts of overwatch fire - meaning they're the ideal front rank to take the kills, get the shots in, and shoot up any counter-assualt units your enemy has. They don't loose that much killyness in combat, and they form a nasty skirmish screen for the choppa-armed boyz in the second wave.
My one warning is that with only a looted wagon on the table, it's going to go down like a sack of squigs every time. People will look across the table and see that the only viable target for all their long-ranged anti-tank is a single fragile rhino chassis with an extremely dangerous battlecannon on it. If it makes it to turn three, ever, I'll be most impressed. When the superheavies are on the board it's a lower priority target and may last long enough to achieve something, but not on its own.
