Please go through Java: theory of Operators, Precedence & Associativity
for other operators and basics of belowmentioned operators
Q1: Increment operator?
Q2: Decrement operator?
Q3: Facts?
Increment operator:
: used to increment a value by 1.
: 2 varieties are available that are preincrement and postincrement.

PreIncrement: value is first used for calculating the result and then incremented
For example X=42
y=++X
step1: x=x+1 (x=42+1=43)
step2: y=x (y=43) 
PostIncrement: value is incremented and then calculated the result
For example X=42
y=X++
step1: y=x (y=42)
step2: x=x+1 (x=42+1=43)
Decrement operator:
: used to decrement a value by 1.
: 2 varieties available that are predecrement and postdecrement

PreDecrement: value is first used for calculating the result and then decremented
For example X=42
y=–X
step1: x=x1 (x=421=41)
step2: y=x (y=41) 
PostDecrement: value is decremented and then calculated the result
For example X=42
y=X–
step1: y=x (y=42)
step2: x=x1 (x=421=41)
Facts:
F1. Nesting like ++(++a) is not allowed
error: unexpected type
F2. Can be only used with variables.
program.java:9: error: unexpected type
a = 34++;
^
required: variable
F3. Can’t be used on final variables
error: cannot assign a value to final variable a
F4. Can be only applied only on all primitive data types
error: bad operand type boolean for unary operator ‘++’
Please comment if you have any feedback or suggestions