Thank you very much for the video and the reply!
I realize now one area where I really messed up, I somehow got it into my mind that you have to mix water and biostuff to heal, which yields a little bit of healing, but as you show in the video, pure biostuff is sufficient and heals a large amount, making it much easier and faster to heal during combat.
I also did not think to mix more than 2 chemicals. And melee'ing bomb enemies with freezing seems like a very effective approach (but also one that could also go wrong if you mess it up given that you are getting close to explosive enemies). I think melee'ing with freezing would have worked in the small room where I encountered 3 enemies during my medium difficulty attempts, which would indeed make it a skill issue on my part (I did not think of combining melee and freezing).
Electricity looks really powerful.
Sorry about the video link not working, I am trying out different free sites because I am a bit of a cheap skate (also this is a temporary account). Does this link work? https://uploadify.net/bda6fd7ca445c1e9/enemy_stuck_inside_wall.mp4