Since I only have a limited amount of time, I'll only awnser Q.5!
Rotation is a gamemode. Only the 5 newest card expansions are usable in Rotation meaning that all cards released in Rise of Bahamut will not be available after the next card expansion coming out in approx. 2.5 months.
- Midrange better than control.
- Spinaria is used when you have several artifacts in your hand and you can clean easily the opponent board, but just Spinaria on the board and evolve its solid.
- 3 Deus is the best because its the most important card in the deck, for always draw new artifacts and full your board (combo with acceletarium is insane).
- In early game you just put artifacts in your deck and wait for Deus. This deck have almost unlimited number of cards so you must control the board and maybe face with radiant artifact. You win when your opponent can't clean your board nearly all time or can't face due to mystic artifacts for exemple.
- All portal cards will be rotated out in many months so dont worry.
I'm not expert of artifact portal but I'm in AA3 and I've seen many of them, different decklists exist you can make your own but keep card which are in all portal decks like deus, icarus, acceletarium, etc.
Im going to focus on how to manage resonance cuz its probably the most important.
- Allways discard your hand after you play deus, the cards in your hand are either too heavy or not that important.
- Once you have played deus ask yourself at the start of every turn if you want to redraw your hand, if your cards are heavy or you dont have a lot then yes, othervise no.
- Only keep heavy cards (safiry,empirial) if you can play them next turn, othervise its ok to redraw, Even if its the last copy, they wont be worth anything if you die cuz you had no answers.
- Dont dump your hand if you dont redraw, it might be more efficient to spend all your mana but you will probably just lose if you dont have a lot of cards in your hand next turn.
- Adding/removing an even number of cards will keep resonance as is, an odd number will switch it.
- If you have resonance just play your resonance cards this way you allmost cant srew up.
What I found so far is that Artifact Portal is a charming hybrid between Control and Midrange. They can't constantly destroy things and throw Banes around like C. Blood, so Aggros can make quick work of them before Deus comes. They can't spawn Zambies and Skels for days like Mid Shadow, so Controls can shut them down if they run out of Acceleratium.
On the other hand, they have pretty solid answers to most things, especially if they manage to draw into Artifacts and get the draw engine going. The Resonance also provides pretty nice Midrange-like pressure, but instead of flooding the board and gnaws at resources slowly, they scare people from committing with Subs, Resonance D. Cuts, and Puppeteer Strings. All in all they're a fun little toolbox, just like the first impression these cyberpunk cards gave me.
sorry if this is a reply but this is an answer to the main question . as a protal craft player you need to know 3 things .
1. your deck will screw you over due to the lessening of chances to draw needed cards (by placing artifacts in your deck) you increase the chances of drawing unwanted cards (if you want to clear this bahamout on the board but get a stupid artifact instead as an example)
2. you must know how to manage resonance (this basically means play the deck more than just 1 to 2 times)
3. avoid too much of the other artifacts and focus on the analyzing artifacts only (other artifacts are ok but will screw you over due to their cost like radiant or mystic which cost 3 and 5 ) since analyzing artifacts help you draw your cards more and are most useful
all in all portal is not that good in the meta for now for 2 reasons
1. the screw up with very few cost effecient cards to get you artifacts (mechanized soldier on 3 or icarus evolve on 4/5 . hakrabi is ok but i really wan to replace her and deus is fffffffffffffffffine but not that fine ) so you need something like an amulet that costs 2 or 1 that can get you artifacts per turn then you will start seeing its power
2. you almost most of the time wont win if you dont draw properly (this can happen to any faction but for the sake of just portal this happens more often than any other faction you want to invest in so keep it in mind ) basically prepare your salt mines and be ready to activate the machines
thats my take on portal so far they get screwed by alsmot all other factions except swordcraft because you can do what they are meant to do 10000000X better by making boards consistently to the point they cant clear at all . so yyyyyyyyyyyeah other factions youre just ded . oh though you can beat the midrange shadow (few times not often) if you are decent in the portalcraft mechanics . but not the other 6 . sorry if its a rant but its kinda the fact that portal has no deck organizer card to help pumb out the artifacts into the play . so you will start veryyyyyyyyy slow .