The St Louis is a bit unique, some would say OP, it's a protected cruiser so it has all of those guns and great armour (for its tier) as well. This combined with the South Carolina not being very good does skew things a bit. With the Wyoming you'll have 12 guns instead of 8 and nearly twice the health of the tier 4 US cruiser.
US Battleships basically come in two varieties, Dreadnoughts/Standard-type (South Carolina-Colorado) and Fast Battleships (North Carolina, Iowa, Montana). The first group all go around 21 knots because they have more armour, and yes they do have shorter range. However, whilst the Kongo (tier 5) for example has over 20km range vs the New York that has 15.6km, his actual best range is probably somewhere around 10-14km to hit accurately at distance so it isn't like he'll be landing every shell on you from 20km away. Once you get to the North Carolina it changes, they start going 28-30 knots and have over 20km range as well.
I would give both the Japanese and the US battleships a fair go (up to tier 5) as the Kawachi and the South Carolina are just not representative of battleship gameplay even two tiers later, let alone high tiers. Certain things do remain the same though, slow rate of fire and having to take a lot of damage, but that's what your huge health pool is for, careful use of the repair abilities and not sailing off on your own or into areas that give destroyers an easy opportunity to torpedo you.
Carriers, best to look on youtube, they play like a top down RTS and it's fair to say that isn't for everyone, and you have limited planes. Once they all get shot down they're gone.
This guy's youtube channel is probably worth some of you checking out, particularly his videos called 'Captain's Academy' as he explains a lot of the concepts such as armour angling, shell choice etc.
https://www.youtube.com/playlist?list=PLoRQa0D7yVpc05KETkgPsyZHIRZd980cO