It's very easy to be legalistic because there are canons and clerical practices of spirituality that makes it so much more simpler for there to be certain standards, but the fact is that, and I think both Orthodox and Catholics agree in principle, legalisms are guidelines, not necessarily "the Rule". You're not doomed to hell if you don't fast, but it would help you to fast.
Same thing with Soteriology. While there might be emphases on either side, I don't see any essential doctrinal disagreement between Orthodox and Catholics on this one. There has been too much misinterpretations from both sides. Orthodox accuse Catholics (and sadly St. Augustine) essentially of Calvinism, and Catholics accuse Orthodox of Pelagianism. The discussion and accusations I find are fruitless.
If you ask me, and anyone who has had many good and kind discussions with Catholics, the main issue is Petrine Primacy. Everything else is secondary.