Returning player with some questions

[Mogli-genjuros]

Hello,i’m ready to start my BFA experience with 2 friends(one is new player,the other stopped at cata).Casual player,just wanna get some toons to 120(get some gear for the ones i like better) and obviously have some fun in the process

Last time i played was during late WoD,i boosted a warrior to 90 then lvled my alts to 100 and played with garrisons as everybody did making gold,some BGs,pet battles etc.

1. I had all the prof on my alts,Should i lvl a specific toon for his prof first? For example my warrior has tailor/ench for farming old content and dis,my druid always had min/JC(since TBC),hunter has herb/alc for transmutes.DK,rogue,lock had randoms and eng for pvp.

   2)Does it worth boosting to 110 my existing 100s ,my pala at 77 mage at 60 or just keep it?.I have some free time and heirlooms.I read that 100-110 lvling can be done with invasions for my alts.Do i need a 110 character to unlock them and do i need flying?.Because no way im doing legion pathfinder.Probably will not even bother with BFA pathfinder.Is lvling with BGs “viable”?.My rogue went 19-85 this way in the past.As you understand im not lore guy I used to gear alts with random BGS but i read that this is not an option nowdays.

   Sorry for my english…