You could land and be surrounded inicially, and nothing could be done exept abandoning such mess.
Agreed. I abandon ~50%. Many of those are before the enemy gets a turn, a few are even before I take a turn.
Hunting for aliens with 4-5 units in kevlar and with Glocks is a roulette.
4-5 in kevlar is missing the point. I've suceeded with 2 rookies, both in suits. Of course you bring as many as possible though. The goal is to take a single alien corpse, worth more than double their lives. Wearing kevlar gives maybe a 5% extra chance to survive here, it's not worth the $, much less the TU loss on rookies. I don't bring meds either, just the heaviest weaponry you can get for <10k. Even though the sectoids can frequently 180 and oneshot your soldiers after getting shot, if they miss or you brought a lot of men you can kill one of them in 1-2 turns after spotting them. If they shoot at you and you don't see them, you abort, because you won't be able to overwhelm them. And this will more or less be true whether you send 2 men or 6 after them, hence why doing it with 2 is not so bad: you only win through a lucky surprise attack anyways.
There's definitely a luck factor in getting enough UFO spawns, especially if you don't have a ready private car. Solaris plans to change that though. Anthropods do seem a bit easier, insanely durable but at least they don't kill/notice all your agents before you can react as often.