1.) Best positioning of bases is where you expect to find the aliens. You should make it a goal to cover all land on the planet with radar. The most important pieces of land are the funding nations and land near them. Europe is densely packed with multiple funding nations, so successful missions in Europe tend to increase your funding a lot. The USA is the largest funder while Canada and Mexico also pay you, so North America is pretty valuable. Europe, Asia, and Africa make a large amount of land all close together, if you have a base in the center of that landmass, your interceptors can reach all the way to the edges of it. Alternatively, you can cover the whole place with 3 bases if each has a large radar: one for Africa, one for Europe and the middle east, and one for the rest of Asia and part of the southeast islands.
Your second base ought to be far away from your first base, to improve your total world coverage.
If your base is near the edge of a large region, your radar may not cover the region very well and aliens may perform missions there without you knowing about it. You can see the list of world regions in the GRAPHS tab in-game, if you're seeing UFO Activity in Areas, or X-Com Activity in Areas.
2.) Some missions are scripted to happen automatically but throughout most of the game the alien missions happen in a randomized pattern. When you start a new game, an Alien Research mission begins immediately, focused 100% of the time in the same region as your base. If your base is centered on the region and especially if it is a small region, you will almost always detect a UFO near your base within the first few hours. It will tend to be a small scout, and it is the first UFO that appears for that mission.
If you see a lot of UFOs congregating over one area and landing, they are probably part of an Alien Base mission. You can run multiple ground missions on the larger UFOs to recover lots of valuable resources and items, and once the mission has progressed far enough, you can have an aircraft patrol over the area to discover the fresh alien base.
3.) There is no difference between left or right hand.
4.) Smoke grenades and other grenades do not work very well against elevated targets. Explosions occur only on the same elevation as the grenade. You can change this in the openxcom advanced settings, by changing the explosion height. I recommend doing so--the original game didn't have this feature but nearly everyone will agree that it should have.
The game is great in many ways, as I see you are discovering. But there are a bunch of areas where the balance falls short or fails completely.
Air combat is pretty poorly implemented in my opinion, and throughout the game you'll find it's generally pretty easy to shoot down UFOs. Catching them isn't always quite so easy, however. Once you research and build a new aircraft and the new air weapon, it'll be really easy to take out everything except the largest UFO type. Even before this, you can take out everything other than the largest with only interceptors and avalanches. Very small and small UFOs are easily downed with one interceptor, even mediums usually go down with only one interceptor. You can shoot down a terror ship with 2 interceptors/avalanches, and a supply ship with 3 or 4. The hardest part about shooting down the larger ones with interceptors is getting them all in range while it's moving slow enough.
Stingrays are fairly weak, the main reasons to ever use them are to crash land a small scout or to save storage space. Avalanches use a lot of space in your general stores, but otherwise are just plain better than stingrays. Also, you'll generally only see small scouts (size: very small) get destroyed. Even medium and large scouts (size: small) will generally crash land. If you do manage to destroy them, you get twice the points that you would have got for crashing them, but you lose the opportunity for a ground mission. If you don't intend to go to the crash site, then it would be better score-wise to destroy them if you could.
Incendiary ammo can be used like electro-flares, except you shoot it instead of throwing it. Larger incendiaries like the incendiary rocket have such a good spread that they light up way more area than an electro-flare. The fires you start will mostly just go out eventually but they can spread a bit and light up even more terrain. I haven't found incendiary to be that useful for lighting but it has potential benefits.
Incendiary damage is very weak. It is randomly 1,5,6,7,8,9, or 10 damage. In the original game it was the same possible values, except 50% of the time it was 1, and the other 50% it was 5-10. Reapers are a bit susceptible to it but otherwise the only enemy it's useful against is the sectopod because it penetrates armor. It'll take a lot of incendiary to take down a sectopod, but other weapons often don't do any damage to it at all, so it's the difference between it being difficult to kill vs impossible to kill. But the best thing to use against sectopods is powerful laser shots.
Psionics are also pretty easy. It'll seem scary when the aliens use them against you, but once you get your hands on psionics it makes the game almost too easy. And that's generally true of the late-game, it gets pretty easy. The aliens start trying harder to go against you, but you get so powerful you don't care.
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I put a lot of work into a mod for the game which attempts to preserve the unmodded feel of the game while fixing the game balance issues as well as adding a larger array of stuff so that you have more choices in the game, and I've been looking for a fresh player to try it out for me. If you're interested, here's the mod page:
[UFO MEGAMOD] Reaver's Faithful MegamodI tried to leave the game at about the same difficulty overall, however some things are easier while others are harder. The length of the game is significantly extended which fits well since there's more content overall. Air combat with UFOs will be more difficult--not difficult per se, just not stupidly easy--so you'd be getting your own aircraft shot more during combat. There's also more reason to use stingray missiles. Avalanches are weaker and more erratic, stingrays are potent and accurate but their drawback is having to get into danger range to shoot. You also get two interception craft: the interceptor and the punisher, both are weaker than your interceptors in the original game but if you learn their differences and use that to your advantage, they are still very capable aircraft.
The mod always gives you choices like that: stingray or avalanche, interceptor or punisher, pistols or rifles or heavy cannons, and all of them are great when used properly but it's up to you to decide which things work best for you, or perhaps you'll use different things in different situations.
I made psionics more difficult. The aliens using them against you might seem a bit stronger, but mostly when you start using them it'll be tricky to really get good psionic capability. Your soldiers will fail psionic attacks more often, and your best soldiers won't be able to mind control the strongest psionic aliens.
