Carlina K,
The higher RG cores in Lanemaster/Legends balls are there to balance off the strength of the coverstocks. I'd suggest that in general do not try to separate the two; go with the ball reaction that you can learn about, for each ball.
Yes, their balls have coverstock and core and nothing in between.
The coverstocks on the BB and the WC are very strong. Both need at least medium-heavy oil to be usable for most bowlers. Both are oilers that get a little bit more than average length and both have a VERY hard arc off the breakpoint (I won't say "off the dry", since they do not seem to nee much dry to make the turn.). If they are not making the turn, you either polished them too much or are just not using them on enough oil. (I have taken my WC to 2000 grit abralon and am still looking for enough oil or enough ball speed.
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Regarding your assumption that the WC is for medium to medium-heavy, I'd suggest that might be true if you are speed dominant or have a LOT of tilt and/or rotation in your release. For the rest of us, it needs a lot of oil or sheer speed.
As for a ball that will be similar to your BlueBerry and handle wet/drys for medium oil, I'd suggest the Absolute Power (medium-light to medium oil with no problem, but no unusual drills). Mine is drilled 5x5, pin under center of bridge and it handles, for me, precisely what you describe. (me: medium speed, 250-300 rev rate, 45 degree rotation, 20 degree tilt). For a little more overall ball strength (in case you have higher ball speed), the New Standard2 is a good choice: it is a strong control ball for medium to medium+ (longer) oils. Both are arc-y balls, which is what's needed to handle wet/drys.
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"None are so blind as those who will not see."