At the meter, behind the deadface plate, there is a bar connected to the panel on the load side. A bare copper wire that is stapled to the pole and runs down into the earth, and the grounded conductor (neutral), are both attached to this bar. So, yes, I see how the bond between ground and neutral is accomplished at this panel.

However, I can also disconnect all power at the next panel downstream where the main service feeder is split into two feeders via the 30a double pole breakers to serve each side of the house. Of course, I have to throw *two* switches to cut power at that panel.

The reason I want to replace the old 70s era Zinsco panel in the washroom, is because I've read that this panel box is a major potential fire and electrical shock hazard.
http://www.inspect-ny.com/electric/Zinsco.htm

Besides the frightening information I found at the link above, The wiring into and out of the box itself is very poorly done. For instance, the romex branch circuits that emanate from this box are run through the knockouts with no cable clamps, and on several of these the sheathing is stripped back as much as 6 inches so that the wires themselves are in direct contact with the knockout holes. Very sloppy and very dangerous for obvious reasons. In addition, the wiring inside the panel looks like someone just tossed a handful of spaghetti in there.

Wouldn't hurt to have a main breaker downstream from the one at the pole would it? At least I could shut off the power to that side of the house without going outside. Or, is there some rule in the code prohibiting it?

I'm not sure what you mean when you say you have to throw two swithes to shut off the panel downstream, please elaborate. I any case you're still better off getting a main lug panel instead of a 100a main breaker since it is only being fed from a 30A breaker. If you want to have a disconnect at that panel then just bring your feeder into a 2 pole 30a breaker and just don't connect anything to the main lugs.

Way too many problems here to try to piece things together. You've got wire from the meter that is too small for 100A, you've got a panel in the washroom, you are undersized for the home (two 30A?). Your best bet is to scrap the whole thing and start over.

That being said, here are some answers FWIW: You have a disconnect at the meter that feeds a remote panel between the house and the meter: this can be fed with three wires (hot, hot, neutral) as long as there is no other metallic path between the two. The neutral and ground would be bonded at both locations. You should have a grounding electrode at this location also.
This panel now feeds two other panels at the house, which is detached. These can also be fed with two hots and a neutral if there are no other metallic paths between the two and it is not a mobile (manufactured) home. Each of these panels must have a disconnect and the house must have a grounding electrode system that bonds the two panels.
If you going to replace the Zinsco panel, please get it out of the washroom.
If I have omitted anything I am sure Petey will speak up :).

normel, your observations and understanding of the present set up seems accurate. The remote distribution panel between the meter and house used to be a 60a cartridge fused motor safety switch. After identifying the wires from the safety switch to the house as being rated for only 30a each, I replaced it with a SquareD 100a load distribution center (HOM612L100RB), in which I installed the two 30a double pole breakers, one for each feeder (the safety switch was ruined as explained earlier). At the time, it seemed to be the safest quick-fix solution to get the power back on inside the house. (These two breakers are the disconnects for the individual feeders to the house that I wrote of earlier, manchild.) I figured that if the load on either one these two feeders were to exceed their 30a capacity, the respective breaker would be tripped at the remote panel, thereby preventing a potential fire/shock hazard due overload.

Since the single service feeder from the meter box to the remote panel between the meter and the house is not rated for 100 amps, could I temporarily improve this situation by replacing the 100a breaker at the meter with a 60a breaker? I think that the #4 AL is supposed to be able to safely carry 65 amps.

I have no idea how to go about relocating the replacement for the Zinsco panel outside of the laundry room. (I may have caused some confusion by previously calling the laundry room a washroom. Sorry about that.) Is there any approved method of extending the branch circuit wires so that the panel could be relocated, or is it okay to have a panel box in a laundry room?

Thanks again guys, for trying to help me out with this challenging problem.

The laundry room may prove acceptable if clearances are maintained around the panel (think of a refrigerator sized space in front of the panel). Reducing the size of the breaker at the meter is an option, but since the panel it feeds has only two 30A breakers, the feeder will "see" no more than 60A. Just don't add more or increase this panel until everything is updated.

Okay, I changed out the 100a breaker at the meter, replaced it with a 60amp breaker. Now that breaker is not oversized for the #4 AL conducters.

Now I bond the neutral and ground terminal bars to the remote panel (the one with two 30a breakers) and to the grounding electrode I have installed at that location. I also isolate all of the neutrals from the grounding conductors downstream within the panels inside the house by terminating the EGCs to the newly installed ground bars, and bond the EGCs to the EGEs at each of these panels.

Does that sound about right?