Existing home wiring is a mess...

yes.

if in fact it is your intent to 'wire it all back to the panel' and hire an electrician to energize it i would suggest you make arrangements with said electrician beforehand.

you see, we are usually held liable for what we energize, so in effect the electrican is vouching for your work.

good luck

If you do not have a problem tripping your breakers, and the wire sizes are correct, there is no hazard having "multiple" circuits on one breaker. One thing to check for is that the breaker lug is listed for more than one wire (read all the little tiny labels on the breaker). If the breaker isn't listed for 2 conductors, you can make a splice so that only one wire goes to the breaker.

There is no limit to the number of receptacles on a circuit in a house, your local code may vary.

If you have some circuits that appear to not be in use, disconnect them, remove them from the box & cap off the ends, also close off the hole in the enclosure. Now you can split up a few of the doubled up circuits.

Splicing in the panelboard enclosure is permissible, so short wires shouldn't be a problem.

When the customer supplies the material, I deduct what I would pay for the material, which is usually less than what you will pay. Also, my warranty does not cover any customer furnished material.

Tom

Well, with the remodeling, I want to add outlets and light fixtures to those that already exist. The residential construction handbook that I have recommends no more than 8 outlets/fixtures on a 15A circuit, and if I want to add more I have to change something. The aluminum is another critical change. I'd rather rewire with 12 ga wire and run 20A circuits according to the specs I have, and know that it's the best I can do rather than simply leaving AL wire in use and cramming more stuff into circuits that I believe are maxed out already.

The critical problem for me is the panel. I have 18 breakers totaling 370 amps in a 200 amp rated box which uses a 60 amp breaker as a main power shutoff. So no matter what's in there, if I have AC, oven, range and a few other things on I'll exceed 60A and trip the whole house. There's no main power switch other than this 60A breaker, and I strongly suspect this is a NEC violation. AL wire in that box for feeder cursuits is clearly a violation.

I'd like to run new feeder circuits to address the above problems and upgrade the box to one that has a main power switch, and has some extra space. Part of the basement remodel is installing my dream aquarium which will need a new circuit, and there's currently no space in the existing box.

I'm doing as much of this work on my own as possible since I'm not made of money and enjoy the effort. Wiring isn't hard, it's just attention to detail and knowing the proper methods.