Earliest craft that can shoot down shippings: LITTLE BIRD (Assembling the Bird), on average takes 30 research, which is pretty expensive for an early game topic. The upside is that the craft comes with a built-in weapon, so you don't need to research any. Also, every mission with this craft rewards you up to 12 additional glamour, which is the most of any craft.
Theoretically, if you get lucky with interrogations and hit Shadowmasters, then getting codex craft is faster than getting Little Bird, but don't bet on it. Still, researching a codex can net you a useful craft weapon.
Researching "Contacts: Car Thieves" will allow you to purchase several other craft, some of which can carry weapons, but to actually get weapons is difficult. You would have to get lucky with events or armed crafts landing. Researching weapons, even simple Airballs, is so far down the tech tree that it's best to avoid if you can.
Oh and, if you chose Peasant Revolution!, then obviously HARVESTER, tho again, getting the weapons is the troublesome part.
Expedition craft is too slow, so not really viable unless the mission is right next to your base. Do buy some recon expeditions tho, those are a good investment.
Making money, invest into constructing additional Extractors and fill them with runts. Research Chateau de la Mort ASAP, so that you can craft it from Apples and sell it. Capture most enemies instead of killing them and sell/rob them. Plantation is actually less profitable than building a Hangar, since Hangar gives 10 workspace, and the 10 workspace with 10 runts will (producing wine) make more money per month. Brainers also make money, since researching stuff gives you infamy (each point is worth $333 at the end of the month), they typically pay for themselves. If in March and you still only have 3, it means you fucked up. You get plenty of Castaway Gals through missions, and each of those can be manufactured into a free brainer.