its posable that 100amps direct burial cable (copper at your best) in my sugestion should be a minium size of 2/0 and ground size of #2 this is stepped up for voltage drop concerns.
check your authority first prior to any work ,
for 100 ft i would use a minimum of 10/3 if not 8/3
8 ga
If you have 100 amp wire, you can use it for a 60 amp circuit, or for any circuit of 100 amps or less. But if you have a 60 amp circuit, 60 amp wire is thinner and cheaper than 100 amp wire.
AWG 4 copper.
That can't be answered until you state the voltage.
Assuming its copper. Number #3 or #2 is fine
12 gauge underground wire or if you think you will ever add any devices to this circuit use 10 gauge.
8 ga
Depends on the size of the circuit which you did not list.
If you have 100 amp wire, you can use it for a 60 amp circuit, or for any circuit of 100 amps or less. But if you have a 60 amp circuit, 60 amp wire is thinner and cheaper than 100 amp wire.
AWG 4 copper.
That can't be answered until you state the voltage.
Assuming its copper. Number #3 or #2 is fine
I would use AWG # 4 copper.
Use the Related Link Website. At the same website check out wire size calculator. You need a #8 wire to get a full 30 load at 100 feet.
That would be a 40 amp 220v circuit. Circuit breaker is 40 amps and wire is 8 awg. Should use solid copper wire. Follow oven installation instructions.
It depends upon the length of the circuit, but for 50 feet or less a 10 gauge wire should be fine. A short length (15 feet), you could use 12 gauge. If you double the length to 100 feet, you should use 8 gauge. A rule of thumb is to drop down a gauge for every length that is doubled. There are wire size charts available on the internet. Some can be conservative such as recommending #8 for 50 ft or less at 30 amps. It is better to be conservative than to run too much amperage on a smaller wire that can cause a fire. As a general rule, 12ga wire can be used in house circuits for 20amps or less. 16ga wire can be used for 15 amps or less such as lighting circuits. That is considering lengths of less than 100 feet.
A 100 foot fish tape and wire lubrication will be needed to make this wire pull.