Advice for a noob

Hey all, I'm looking for some help. I am extremely new to vaping (like a few weeks). I have a vaperesso 3, and it's working fine, but I can't help but think that I might like something a bit better for use when I am at home (which is a lot of the time). So I'm looking at getting something like a Vaporesso Armour Max.

Now keep in mind that I know fuck all about all this. I just bought a bunch of juice, and because I'm a noob I asked for it to be 50/50, even though 70/30 was an option. I've mixed this to be 12mg

It seems like "everyone" suggests 70/30 is better with this sort of setup. What happens if I use 50/50?

What coils would be best for me to get? They have 0.15 (75-90w), 0.2 (60-75), 0.4 (50-60) and 0.5 (30-40).

Any help appreciated.