All buck rubs, naturally. Rubs are used to build up neck muscles, territory and show dominance. They are not done to remove velvet, velvet will just fall off. Velvet is the area in which protects and provides growth to the antler. Once growth cycle is reached, the velvet's blood supply will stop and the velvet will die. While it is true it can be rubbed off, it is pure coincedence..as the loss of velvet is the early stages of Pre-Rut.

Judging rubs to deer size and maturity is somewhat possible, but not an exact science by any means.

Younger deer will tend to:
Attack small sapling and trees
Rub closer to the base of the tree
Make square rubs in shape and hardly get the rap around effect
Their rublines tend to be sparse (hit here, hit there, etc)

Mature deer:
Stages, first the samplings, then smaller trees, then the big stuff as the neck needs more work.
Saplings are snapped off
Rub closer to eye level
Up and down the tree
Rectangular shaped rubs, with more rap around on the tree base
Rublines are very distintive and heavy. (you'll often see several trees in a line or immediate area that mave been worked)
Gauge the rubs by the hieght the reach, look for scrapes with high up snap twigs (or licking branches)

As far as roaming together, i think a lot depends on the herd of a given area. But it is fairly common for the small ones to sort of tag a long with each other...maybe for safety or the old....I don't know what the heck I am doing thing..learning the ropes. A big deer isn't overly concerned with these little guys, once he arrives the only thing that matters is the one that stands his ground...the rest are blurs in his vision. Dominant bucks will resort to fighting as a last ditch effort to win the breed rights. They often hunch and circle, stare and grunt at each other,etc. This is often enough for the littler bucks to "Say No thanks". If a buck approaches a given area sheepish, he either knows a) he's running thin ice or b) he's had his a$$ kicked before. So they very much know the score well prior to the rut being even full bore. This is not to say they don't try or have the urge to breed..they just wait their turn or if an opp. arises they are in. NAother reason why I think the little ones hang together, they may happen upon a hot doe and they then have a chance to breed...provided MR. BIG don't show up uninvited. Cause then it is may the best d!nk win!