OK, I can only handle the bucket topic at the moment. I'll have to come back to the horizontal vs. vertical situation later.
Thanks for the great topic Front-Ranger and the summary in the first post. It occurs to me that somewhere else someone noted that there are often not only buckets but coffeepots or pitchers (some vessel with a spout). The idea was that Ennis was associated with coffeepots and Jack was associated with buckets (although I can think of lots of ways that could be reversed). I guess, the idea was the Ennis is the vessel that pours while Jack receives. These two symbols become really clear in the Flashback.
I *just* finished watching the movie and had buckets and coffeepots on my mind. So, here's a list of the buckets I remember. I'm repeating some things from the posts above (but I thought I'd be systematic). I noted these things because the camera seems to linger on these props during these moments and/or the item is mentioned in dialogue. I'm sure I'm missing some, but...
-Jack with the two full buckets of clear water that he sloshes next to Ennis building the campfire
-Ennis washing the coffeepot out in the stream when he looks up and gazes at Jack way up high on the mountain with the sheep
-When Jack comes in for supper one night and complains about how bad the pup tent smells, etc. he makes a big point of opening the coffeepot lid
and looking inside and then he pours himself a drink
-the buckets during the "that's the most I spoke in a year" conversation. The buckets are in the background and it seems that Jack may knock some over when he falls to the ground.
-Ennis kicks a bucket or pot (can't tell which) when he stumbles into the tent for the 1st tent scene
-when he opens the tent flap the morning after the 1st tent scene the clearest object that can be seen near the fire circle outside is a bucket.
-the "slop-bucket mouths" comment during the fireworks scene
-the bucket of ashes that Ennis kicks while the girls are on the swing set
-the bucket that Ennis has to chase downstream while he's washing dishes and has the argument with Jack about moving to Texas
-Ennis's comment that the most traveling he's done is "around a coffeepot looking for the handle"
***THEN- in the Flashback*** As the camera pans up from the fire towards Jack's face, it reveals a bucket and a coffeepot sitting neatly side by side.
-one final possible bucket (though it could be a stretch) is the large metal garbage can outside of Ennis's trailer at the end.
Yes, I think a lot can be made of these metaphors and the way the symbols change throughout the film.