Hi, there - last question answered first. Yes, 4051 and 4052 are
slightly bigger - but this is because they're handicap cabins. HAL won't prevent an able bodied person from booking them, and also won't "bump" if a person in a wheelchair who needs one requests it...so, it would be better to leave these for those who need them. Because of the "odd" layout for a wheelchair, these rooms aren't as well configured for the able bodied, anyway - I believe there is no sofa, just a chair.
On the other hand, 4053 and 4054 are regular cabins. They tend not to be popular because your view on one side features the nose of a lifeboat, but I like the fact you only have a neighbor on one side. I think the balcony is a hair
bigger, but for really large ones, you have to book a VA on the stern. Also, 4164 and 4166 have double sized balconies, because they abut a crew stairway - but these usually get booked out fast.
6001 and 6002 have very odd windows, which are deep "tunnels" and - you're right - are hard to see out of. On the other hand, you have a "free" verandah just steps away.
Hope that helps - searched for photos to illustrate, but came up empty today