Baseball players do use the on-deck circle and they use it to prepare for their at-bat. Some players just stand there and do nothing, but this is not the purpose.
yes
Although each sanctioning body has their on rules you are typically limited to 2 bats when warming up in the on deck circle.
A baseball glove
Wristbands.
most baseball players use bamboo. maple and hickory is used alot too. but ash is the cheapest.
Redman
Wood
Because of the size of the field that baseball is played on, the use of a softball would be irrational.
No MBL players use Old Hickory bats and gloves.
To enhance power and stamina
there are many players in the mlb that use steroids. My guess would be 30-40.
100% of those who get hits use bats.