just started back playing, been gone like 6 months. do arena wins count for the "standard" wins for new expansion pack quest. also which packs are worth buying, or should I just use all gold on arena runs. have naxx, brm, league expansions.

Depends on how big your collection is honestly.

If you aren't playing wild, dust all that old stuff.
Arena is wild so any quests with standard don't count.

Classic packs had a lot of value due to getting full dust value from nerfed cards. Not sure if that's still going on. Otherwise, I'd suggest getting wotog packs as there are a lot of cards being used in the meta

dusting cards you don't have extras is generally a bad idea.

At least I think so, I personally have all the cards so I am not 100% sure.

i do plan on playing wild, just completely clueless atm on the meta. was doing the free pack quests first then should I do arena with gold or just buy packs of wotog

I don't think so... If you're trying to play the game with a budget in mind I think its fine.
personally I don't even have 50% of the legends.. but maybe less then 50% of them actually even see play..

I dust shit I don't need...

Multiple times legend..

Some cards are just always worth dusting, like angry chicken. But if I'm on the fence about a card I usually keep it. Like crazed alchemist, which is actually getting play now.

basically what ive always done unless there was something I absolutely had to craft for a deck I was making then id start dusting stuff I probably wouldn't use. still iso if its worth buying packs of wotog with my gold or just doing arena with it praying I get some good runs in

I'd buy packs.

Godbless will shed a tear for the chicken when he reads this post