1) Married batteries, in simplest terms, bought together, charged together, used together, never sepperating from the set, aka don't cheat on the other mates in the set, this applies to dual battery pairs, triple battery sets, or quadruple battery sets. 2 battery pair stay together, not mod specific, if the mod is 2 battery then the 2 battery set together can be used in any 2 battery mod, never use the batteries alone in a single battery mod, this applies for 3 battery sets in 3 battery mods, and we are now seeing quad battery mods, so 4 battery sets. This keeps the same wear and tear on the sets to keep them balanced and equal, one battery sags weaker than the others in the set, puts undo stress on the batteries and can lead to disaster. "REMEMBER" also, that Alien 220watt can not reach 220watts at low battery charge with those LG HG2's, factory rates them at 20amp Continuous Discharge Rating, though independent tests show they are 18amp CDR, low charge before mod shutdown is about 6.4v (3.2v per battery)
18amps X 6.4v=115.2watts maximum
18amps X 7.4v=133.2watts maximum @ 3.7v each battery about 50% charge
120 to 125 watts max will be about optimal with the Alien 220w mod, you will not be using any coil head above the Quad coil, the 6coil, 8coil, and 10coil heads need just way to much power that the HG2 just will not handle without sacrificing the benefit of their 3000mah runtime provides.
2) The liquid condensation being reddish in color, could be many things, carbon from the coils, but the biggest thing would be basic chemistry, take any liquid with food colorings and flavorings, add heat into the mix and you make other chemicals beyond what is in the liquid to begin with. Being a grape flavor you might not see the diluted purple or such from the flavorings in the liquid suspension and the condensation is cumulatively gets darker until the next cleaning. If you see down the stem any rust or exposed brass/or ferros metal instead of chrome or stainless there could be an issue where I'd stop using the tank, don't need to be vaping on a tank that is putting that into your lungs. <-- This is speculative based on your description, it is most likely just flavoring residue as I stated before but still I'd thoroughly inspect the stem.
3) The Alien 220w says it has a balance battery charge circuit on the control board, however I am one of many that say multi-battery mod needs and external dedicated charger, especially for married battery sets, an external dedicated battery charger does only one job, charge batteries, it will keep the batteries in balance far better than any onboard mod charger. Can you use it, short term until you get a dedicated charger, yes, but you'll have to switch the battery positions manually each charge cycle. Use the onboard charger when out and about without a spare set of batteries to swap out, or in an emergency, yes you can, in both instances monitor the mod constantly during charging. Having 2 sets of married batteries for the mod is ideal (4 batteries total).
4) Building coils yourself? You'll need some basic tools, wire, and wicking (most use organic unbleached non-peroxide cotton as wicking). Get a grasp of "Ohm's Law", get on youtube and start watching videos. Basic minimum tool kit you will need is an "Ohm Reader" or Digital Multi-Meter to read resistance (Ohm's), cheap set of jewelers screw drivers, pair of needle nose pliers, pair of flush cutting wire cutters (beading flush cutters and needle nose pliers are good and cheap), pair of good tweezers (ceramic tipped tweezers suggested), and a pair of small trimming scissors (for cutting wicking). A cheap, 10 to 15 dollar clone rebuildable drip atomizer (RDA) would be a good investment as well, more open space to practice with on it, then practice, practice, practice to get comfortable with the motions, the screw drivers can be used to wrap the coils on. Start at higher Ohms and gradually go down in resistance, suggested wire would be Kanthal A1 or Nichrome80, don't mess with Stainless steel, titanium or Nickel200, nor try to use any other wire types, gauge wire either 26 or 28 AWG to start. Wrap a coil, mount it, trim excess lead wire, place on ohm reader or read with the DMM, if no shorts, mount on the mod and pulse fire the coil, crimp with tweezers, pulse again, crimp until you get and even from middle to outside glow, re-read the ohms. Take coil out, re-wrap another and practice just like that, try staying at about 1.0ohms to start, don't go lower than about 0.3 to 0.4 per coil on a dual coil, when mounted together the resistance is decreased in half to two 0.4ohm coils together are rought 0.2ohm when done right.
www.steam-engine.org <--- This will be a good friend to you in vaping, has coil calculator, ohm law calculator, and other valuable vaping apps