70 amp breaker.

Yes. When you remove the breaker you could take it with you so you can get one of the same type and mfg.

A 70 amp breaker might control the single pole circuits of the house other than the dedicated circuits for AC, Dryer, Sum pumps, etc.

Be sure that this 70 amp breaker is not connected under the electric bus to the rest of circuits of the house. This kind of amp breaker (60 amp, 70 amp) are mostly the "main breaker" for several circuits controlled by breakers with less amperage.

I don't see another reason for the existence of a 70 amp breaker in a house electric panel, but who knows. perhaps was installed just to fill up two empty spaces because no blank covers were at hand, but I doubt about this. Perhaps was controlling an additional electric panel somewhere in the premises.

Anyway, if the 70 amp breaker is not controlling anything, then you can replace it by any double circuit breaker or by two single pole breakers, and run the needed circuits.

In case the 70 amp breaker is controlling a group of circuits in your house, and you need space to install another breaker, then you first check the total amperage that the box can handle. This amperage label is found somewhere in the panel box. It can be 100 amp, 125 amp, 150 amp, 200 amp.

If your box is 100 amp or 125 amp, you might need to upgrade the box, but this won't be necessary if you have a gas stove, gas heat, and gas water heater, and the rest of appliances and lights don't pull much energy.

So, lets play that the 70 amp breaker is indeed controlling other breakers, and that you have a 125 amp panel box, gas water heater, gas heat, and gas stove. And you have no spaces to add a new 30 amp breaker.

Then, you buy two single pole double circuit breakers and remove four single pole circuit breakers, and install the wires to the new single pole double circuit breakers.

Doing so, you have obtained two empty spaces, and you can install the 30 amp double pole circuit breaker.

If the 30 amp circuit breaker you need is single pole, then you just need to buy another 15 amp or 20 amp single pole double circuit breaker.

Be sure to buy the single pole double circuit breakers according to the needed amperage, like 20 amp and 15 amp. The wiring in a house is mostly 14awg for 15 amp and 12awg for 20 amp.

Be careful not to install a 14awg wire in a 20 amp circuit breaker.

In electrical installations, the greater the amp for a wire, the lesser the number of its awg. Example, wires that handle 50 amps are #6awg, 30amps wire is #10awg, 20 amps wire is #12, 15 amps wire is #14.

You might need to run a #10awg cable for the new 30 amp circuit.