Reapers... usually they just hang around (well, not literally hanging), but they have some type of attack. It included those typical orange flashes you also get when ethereals try mind controlling your units. But I *think* it just dealt damage, nothing more.
I've finished the game without ever taking a live crysalid, so apparently it's not necessary taking the risks. Though that's a personal choice
It's also a good idea to let soldiers spread in groups of three: if one runs into a crysalid, the two others can still try to take it down in time.
As for mutons early in the game: don't heavy rockets damage them a decent bit (not enough though to take them out in a single shot)? Also, I prefer using auto cannons over rifles (I mean rifles, not laser rifles!) as a few hits with those still have more effect than rifles. A friend of mine once set out with 8 soldiers using only rifles. They all ended up dead while he didn't take out a single muton :whistle: Not me though, me likes heavy rockets early in the game...