How viable are battle tanks and vanquishers? I don't see the classic battle tank appearing in lists very often, or the vanquisher. Would a vanquisher with lascannon and multi melta sponsons be a wasteful point sink? I really like its potential for hunting knights, wraithknights, riptides, wave serpents and all kinds of MC. Are there better ways of spending those points?
If you're bringing Pask, the Punisher is terrifying. If the tank hasn't got Pask in it, then Executioners, Punishers, Demolishers and maybe Eradicators (if you fight mainly xenos - the Eradicator is brutal to almost all xenos infantry) are your best bet.
Are vendettas by far the best way to shoot down enemy air? What other options are people using?
are Sabre Weapons Platforms. Vendettas are still a solid pick. Alternatives? Allies, I'd guess.
Heavy Weapon squads
How to arm?
Don't - they evaporate. If you must must bring them, I'd go with Mortars, because then you can at least hide them somewhere and not have them all die on turn one.
Same question. I'm liking missile launchers on these guys for the AP against monstrous creatures, though I was planning to distribute ML's throughout my infantry units too.
I've always been a fan of the Multi-Laser, but since they're so versatile I think the best advice would be to arm them with whatever gun you're missing from the rest of the list.
Attacking forward objectives
How? I love the idea of a chimera with two heavy flamers carrying infantry though I'm not sure that's very sensible. Don't know how I'd arm the guys inside either, or even what to put inside it
50 Guardsmen, 5 Power Axes, Primaris Psyker, Munistorum Priest, Inquisitor with Tome of Vethric and Hammerhand, Rad Grenades, and Psychotroke Grenades.
Meltaguns, and a bunch of 'em. If you can get side shots with Autocannons or Lascannons, that can work too. Try and surround them with guns so their Ion Shield is minimized.
Meltaguns, Plasma Guns, Guard Blob, Lascannons. Heavy guns in general.
Whatever guns you usually use to bring down medium vehicles. Preferably something with Ignores Cover, but weight of fire works just as well.
Lascannons and combat.
The easiest way to deal with fliers in the new dex is to double up on the master of the fleet as it stacks and if you can pass 2 ld9 tests the chance of getting fliers in on reserves is remote and gives you a chance to just kill everything else.
5+, with any modifiers your opponent's bringing (and with anything more than one Flyer, he should probably be bringing reserve manipulation) isn't a desperately effective anti-air defence. It's good if you're already bringing anti-air and two CCS, but I don't think I'd want to use up my HQ slots for -2 to reserves.