If you like precision (as I do), vaping terminology may cause you some distress. A lot of it is pretty loose. Often it originally meant one thing (that made sense), but as the technology changed the original thing was supplanted with something else and the term was used for the new thing or applied to a wider category in a way that makes a lot less sense.
Take 'mod', for instance. It's from 'modified flashlight', as many of the first mod-like things were just that. Now it's often described as 'that thing you put the battery in.' You can also call it an APV, or advanced personal vaporizer, but mod is the usual term.
Atty/atomizer: The thing that was originally called an atty is rarely used nowadays. Currently, the term can mean either a tank with all its bits or a drop-in coil. For the sake of clarity, I'd recommend dropping the term and using either 'tank' or 'coil'.
Coil: The "little things you have to replace and will never have enough of" are most often called coils, unless you're talking about rebuildables, in which case it means the actual wire coil
Both nic salts and freebase nic can be used in any tank. Nic salts are basically a different chemical form of nicotine that (usually) has less throat hit. It was developed to make it possible to vape higher concentrations of nicotine - if you get high enough, the throat hit will make freebase nic hard (or impossible) to vape. Nic salts are usually used in pod mods or MTL (mouth-to-lung) setups, while freebase is usually used in some MTL and most DL (direct lung, sub-ohm usually means DL) setups. Pod mods are very low power and go through juice very slowly; MTL is in the middle; and DL is high power and goes through a lot of juice. The original idea is that with a pod mod each puff gives you a tiny bit of juice with high concentration of nicotine while DL gives you a lot of juice with a lower concentration of nicotine so you end up getting about the same amount of nicotine either way.
If you're wondering what wattage you should be vaping at, it depends on the coil (and the juice and your personal preferences). Coils usually have a recommended wattage range printed on the box and on the coil itself. The recommendations can be a bit exaggerated. My suggestion is to start at half of the bottom end of the range, so if it says 30 - 45 w, start at 15 or 20 watts. Vape a bit, then increase your wattage. Repeat. Continue to increase your power until the vape starts getting worse instead of better. Then go back to wherever you liked it best. That's the correct setting for you. Don't worry if you're outside the recommended range.
I want to add something to DeloresRose's useful advice. A mod's rating tells you how much power the board can handle, but it doesn't tell you how much power you can use safely. That depends entirely on your battery. Your Aegis Solo is rated 100w, but there are no 18650 batteries that can safely provide 100 watts and only a handful that can provide 90w.
