1. Good call on waiting for M19 to rotate you probably should only run a few to get the Gem rewards if you can crush and get 5+ wins. GoR is up now and you can still get 7 plus wins by just going boros (in a best of 1 aggro wins a ton)
2. Quests I found were the best way to constantly generate gold and allowed me to build my collection slowly but consistently.
3. I have no clue what calculates how much rank you win or loose per match. I'm assuming it's based on some hidden MMR system. As to achieving rank I was able to get to gold 1 in an earlier version of the beta and there were no rewards for rank then. I do not know if it has changed now but I suspect it has not.
4. My favorite of the premade deck is the black blue deck because it allows for card draw and removal once I got a lot of the useless pirates out of it. Still fun to run mono green if I need to grind out wins since removal among the premade decks is limited and inefficient.
5. You can turn on "Full control" from the settings menu under game play and that will make it such that you have to control everything such as tapping lands or responding to spells/triggers.
6. If you want a good way to grind, singleton is fantastic. You can scrap together all of your bombs and make a sweet control deck that will win 5 games consistently since aggro is inherently inconsistent in singleton. Plus if you get 0 wins you are guaranteed a rare and an uncommon. Since it's a 500 gold buy in you basically get half a pack where the only card you care about is the rares and uncommons anyway. I made a solid Esper control deck and I can get 4-5 wins fairly consistently.
1 Drowned Catacomb (XLN) 253
1 Isolated Chapel (DAR) 241
1 Glacial Fortress (XLN) 255
1 Chromatic Lantern (GRN) 233
1 Watery Grave (GRN) 259
1 Thief of Sanity (GRN) 205
6 Island (RIX) 193
6 Swamp (RIX) 194
1 Hostage Taker (XLN) 223
1 Connive // Concoct (GRN) 222
1 Azor, the Lawbringer (RIX) 154
4 Plains (RIX) 192
1 Teferi, Hero of Dominaria (DAR) GR6
1 Settle the Wreckage (XLN) 34
1 Cleansing Nova (M19) 9
1 Mystic Archaeologist (M19) 63
1 Nezahal, Primal Tide (RIX) 45
1 Dire Fleet Poisoner (RIX) 68
1 Vraska's Contempt (XLN) 129
1 Twilight Prophet (RIX) 88
1 Demonlord Belzenlok (DAR) 86
1 Seal Away (DAR) 31
1 Take Vengeance (M19) 40
1 Conclave Tribunal (GRN) 6
1 Hieromancer's Cage (M19) 14
1 Disdainful Stroke (GRN) 37
1 Essence Scatter (M19) 54
1 Omenspeaker (M19) 64
1 Blink of an Eye (DAR) 46
1 Cancel (M19) 48
1 Sinister Sabotage (GRN) 54
1 Chemister's Insight (GRN) 32
1 Sift (M19) 72
1 Divination (M19) 51
1 Radical Idea (GRN) 52
1 Walk the Plank (XLN) 130
1 Kitesail Freebooter (XLN) 110
1 Murder (M19) 110
1 Price of Fame (GRN) 83
1 Ravenous Chupacabra (RIX) 82
1 Notion Rain (GRN) 193
1 Submerged Boneyard (M19) 257
1 Dimir Guildgate (GRN) 245
1 Forsaken Sanctuary (M19) 250
1 Meandering River (M19) 253
1 Dimir Locket (GRN) 234
1 Chart a Course (XLN) 48