I second magnetizing them. I typically don't run more than a lone Ravagore in any list with the exception of maybe eLylyth. The nice thing about the collection you've opted for is that you have some great options.

Saeryn can be run with any comp. She's a very good jack-of-all-trades caster and because of that you'd be hard pressed to make a "bad" list for her.

The only "problem" Legion heavies have is that they each somewhat compete for the same play space. The non-serpentine heavies are 9-12 points, have many of the same advantages, and differ in the kind of utility they offer your army. When you're choosing what to run, instead of melee damage the question becomes "what else do I want them to do?".

You should be selecting your beasts based on your need for their supplementary battlefield role. The Carnivean is great but you're only considering him over the Scythean on account of his animus. Otherwise you're paying 2 more points for one extra pow on the main attack and one less pow on the claws. Ignoring the rat 4 spray anyway. That being said, the animus IS strong enough for the Carnivean to have a viable supplementary role.

When taking a Carnivean and a Scythean, you change your battlefield dynamics tremendously. Now the Scythean can tie up a big portion of the field with that reach, and with Spiny Growth the Scythean is likely to be able to survive the attempt to go through it.

The Ravagore is great but I wouldn't recommend doubling up under most circumstances. He often becomes relegated to "10 point artillery piece" and people forget he's a bigger threat in melee than at range. Additionally, 10 points for a single 3" aoe is expensive, even if it does leave a scather.

As far as building lists is concerned, growing from 15 to 50 isn't too bad, though based on your purchases I think you may have over-done the heavies. Also, I would recommend getting a hold of at least one shredder. It's one of Legion's all star beasts.

Based on what you have, I would get a bunch of games in on your 35 point all in one box. I'd work towards that by starting with Saeryn, Neraph, Scythean, Strider Deathstalker, and two Shepherds for your 15. At 25 use the entire box less the Scythean or Angelius and a Shepherd before playing the full box at 35. Then, play the hell out of the 35 until you get a good sense of what you want your list to do that it's not currently doing. Don't make list changes on the outcome of single games. Play a good amount of games (5-10) with a list before making any adjustments.