Hi there, I have some questions I would appreciate comment on.

I am finishing up a garage remodel that has primarily involved building a proper loft, paneling the walls and painting. At the outset of the project I emptied the garage and removed all outlets and conduit back to the junction boxes at the back of the garage (also the firewall of the house).

I am now getting ready to extend two circuits that I will call 7 and 12

Circuit 7 (20A) is primarily used to power the garage lighting including carriage lamps at the front exterior of the garage (it also handles a hallway light in the house). I will also be adding outlets for a garage fridge, freezer and garage door opener. I'm comfortable this circuit is not being overloaded

Circuit 12 (20A) is terminated into the garage and exclusively powers a 4 outlet box. This is used for the clothes washer, dryer (motor only...gas for heat) and sprinkler controller. I want to extend this circuit to the front of the garage where my workbench is so that I can plug in hand tools and a drillpress. Again, after looking at the devices on this circuit and how they performed in the past, I'm not concerned about this circuit being overloaded

so, here are my questions:

1) In order to conserve on the amount of conduit being run, I want to run hots from both 7 and 12 in the same conduit...is this a bad practice?

2) Do I need to keep the neutral for use with circuit 7 and circuit 12 seperated. That is to say where I am running 7 and 12 hots in the same conduit can I just run one neutral wire (wire nutted to both the 7 and 12 neutrals) and use it with both circuits or should I extend both the circuit 7 and circuit 12 neutrals (not sure how load capacity compes into pla with the neutral)

3) If I am using all metal conduit and boxes, I have been told that these will provide a sufficient ground circuit (as long as it is actually grounded). If this a bad practice? Seems like it would work but I'm not sure it is the best way to go. I'm all for saving some money but if this is not a good practice I have room in the 1/2" conduit to run a 6th wire for gound.

4) I am planning to use a GFCI circuit breaker on circuit 12 but was told that this is not a good idea and that it will always be tripping off. Seems to me like if it is tripping, then there is a problem that needs to be resolved...any reason why I should not use a GFCI circuit breaker on this?

5) I am planning to NOT use a GFCI circuit breaker on circuit 7 because there will be a fridge and freezer on that circuit. I've already lost a freezer full of meat because the freezer got unplugged and we didn't know about it and didn't go into it for several days. My concern is that the GFCI trips and I don't realize it and loose all the frozen and refrigerated goods. I will have exterior carriage lamps on this circuit, althought they were not originally on a GFCI circuit and there was no problem

I know this is long and lots of quests...Thanks for your input!