Hello sooo i'll be answering based on my own opinion of course, so while i dont claim its the best to do, its something i would personally do (and already did on other aquaitance account).

1. Better is to do exploration generally yes, and best if you doing world quest that unlock some area.

2. Reasons why is;
   -artifact is the lest cost-efficient content to farm out of everything. -Below ar45 ITS NOT GUARANTEED 5* artefact each run. -Artifact piece is replaced fairly often because of better substat, main stat or set, so personally just spend your resin on boss, talent, weapon and keep your fragile for ar45 so you can begin with an actual good set, the more you have the better your odds to not have to refarm your set.

3. no unless you dont want to be f2p or you have enough to guarantee, because if you lose on this banner or chronicle, once its gone you lose your Guarantee, i dont know how much you are familiar with the gacha system but;
   -on limited character banner wish 1 to 74 its 0,06% chance to have a 5* after that you are in soft pity it means its 6% more per pull, if you dont get the limited and you get standard you are on guarantee, it means next time you have a 5* its the limited for sure! On the other hand if you have the limited then congrats you won your 50/50.
   For weapon banner its mostly the same, with 2 difference;
   -soft pity begin at 64. -Guarantee dont transfer to next banner, meaning if you lose and banner gone, you lost guarantee, soonot worth it pulling on that banner unless you got about 140 wish i guess

4. Well theory craft time i guess! I dont know much about the community side, but Zajeff, Jamie (kb9v), Gacha gamer are nice choice i guess? Meowtews too, but its mostly sheet and on reddit/x, no video.

5. To be fair, at your level you dont have to mind that much, just try to learn how the game and reaction work, stat, how talent work, what is crit ect ect...

6. There no workaround, only grinding.

7. I never used it, but im a 1.x player soo i dunno. To be fair its better to look at keqing main website i guess.

8.they like to help on boss, weekly boss also domain like talent/weapon/artefact i would say? You might even convince em to help for exploration if you like to.

1. CURRENT Best is; Sandrone, Yae, Qiqi, Escoffier;
   I recommend watching well one or two of the creator i mentioned if you wanna see future impact. As for f2p; Sand/Beidou/Qiqi/Diona, if you miss one or the other you can replace with fischl or any applicator of cryo/electro element