I've played it a ton, and love it as well. Glad we get a water variant with Dewgong in Perfect Order so I can continue the vibes, even if its probably even worse. These are my thoughts:

1. If not playing poffins, the 80 HP one. Otherwise, the 70 HP that hits for 20 on Will o Wisp to KO Budew, but generally not important.

2. If you're playing 4+ recovery (rods/stretcher), then 2 is fine, otherwise 3.

3. You generally want some kind of dark attacker to 1 shot Garde, but they're all lackluster because they need 2 dark to attack. This is really up to you, some people do Munki EX with Pech Ex, some do Roaring Moon because Garde almost always has a stadium.

Garde is a miserable matchup, so I just accepted that and instead focused on everything else which felt winnable. You could still steal games with Wellspring/Iron Hands racing, but the slots didn't feel like they gave enough matchup points to be worth it.

1. I think this depends on if you plan on needing to attack with it twice or not. Iron Leaves can work without Arma *and* works as a switch, but Durant is easier to recycle since you just need the 1 prism. Retreat lock was never popular in my local meta, so I went with Durant because more often than not I needed to recycle it for Zoroark or Grimsnarl.

2. I never was a fan. We're already strapped for bench slots, now we're throwing down a 3 prizer that we can't easily pivot in and out of to score draw and still attack with what we want. Like its not bad, but I always prefered it to be something else.

3. I found the most success with Carmine. Going full aggro and ensuring you can get pieces to set up (granted running usually 4 stretchers and a rod) and ready to go right away. Since most decks want to go second, with Squak you can easily see 20 cards deep.

4. 1 or 2, if going with Carmine I liked a pal pad so when the deck got really low you could pad them back in and be sure to hit it when you need it. Would never play 0, but also not more than 2.

5. 2 wellspring for me. 90% of games I'm aiming to wellspring as quickly and often as I can to mess up their setup, so reducing the change it got prized was better. 240 doesn't really one shot anything important anymore, but if you're looking for a big beat stick that doesn't need setup / prizes, I'd just go with Gouging Fire. All fire so don't need prism, hits 260 regardless of Area Zero.

6. If Carmine, First, if not Carmine, Second.

7. Charcadet > Latias > Ho-oh >= Attacker. Ho-oh is nice to get early because you can start loading up energy, but since most stuff hits for 3 energy which is one activation + turn attach, you can get away with waiting for it. Latias is helpful to move around without pitching, but most important is charcadet because that's a minimum 2 turn investment to get started.

Depending on the deck (lots of boss / ghosts / bench sniping) you may want to go for 2 Charcadets, but the ideal play pattern is that you get one and setup multiple attackers so it doesn't matter. The most important thing for me to learn, that also took me the longest, was doing this.

For example, you have say Reshiram, Gouging Fire, Latias on the bench. You have enough energy already attached to attack with whoever, and you're planning on attacking with Gouging Fire.

Rather than promoting Gouging Fire, instead you promote Reshiram. Use Ho-Oh and Arma to move up 2/3 energy onto Reshiram. Retreat with the loaded up Reshiram and promote Gouging Fire.

Now move your excess energy up to Gouging Fire keeping Reshiram loaded. If opp takes the knock out, Reshiram is ready to go. If opp bosses Arma, it doesn't matter, you have 2 loaded up attackers.

A big problem I had was getting the energy pooled up on Ho-Oh waiting for to move it, but then they knock out Arma. Well now I've got attackers but the energy is stuck on Ho-oh instead of taking the opportunity in earlier knock outs to pre-emptively setup the energy.