I hate to say it because I absolutely love my Orchid v4. But I would recommend a Lemo over the orchid as it is a bit easier to build and wick with the two piece chimney design. And also it is glass, so no worries about tank cracker juices.
Since you are on a mech, and have a good 35 amp battery, i would start with 26 gauge. it is what I tend to use on most of my builds. Make sure you have a way to check resistance though before you attempt any builds. And also, make damn sure your coils are going to be free of the chimney when you go to put your chimney on. If you build your coils to far away from your posts, there is a good chance a coil will touch the chimney upon assembly, and bad things happen.
Take your time, check your resistance, and just be patient. It is an art form worth perfecting, as the results and money savings that can be achieved are highly advantageous! You simply cannot get better flavor or performance from a self built rda/rta! Again, do some research, and then do some more research on whatever it is you are going to try and build. Patience and safe practice is key!
Good luck on your journey man, you are at the point where things start to get really fun. Treasure it!