Like Bert stated 6 is all you need out to the rods 6' apart. Metering block is also the way to go. Then the siding guys can side around and make it look all purdy...
As far as a ****** don't use steel. If you do then you have to bond. Use schedule 80 pvc. Cheaper and it meets code and oh yes...
Just checked out your pic. I don't see where the neutrals are bonded to the can. If they aren't they should be. The easiest way I always do this in the field is to take the neutral lug off and remove the red insulator. Then reinstall the neutral lug directly to the can.
Yes you would have to install 200 amp fuses to protect that size of wire. I'm pretty sure you just had a typo on the wire - I'm assuming you are doing a single phase panel so you only need a 4/0-4/0-2/0. BUT since this panel that you would be installing is still a subpanel you will also have to...
Just run some #1 alum SER like Bert said. It will meet code and will be more than enough for what your doing. You got to remember one person can only run so many things at once.
As far as running larger for future - if you have a 200 amp main, the largest sub you can run is 100 amp. So you...
What I do is find where the 2xs are for backing so you know you will hit something solid instead of just tin. There should be a pretty straight line of screws going horizontally across the building where they secured the tin. You could just undo a screw and install a 1 hole strap. That would be...
Only need a 6 bare to the rods.
You would have to do all the work for the power company. They would pull the meter and you would change everything and have them come install meter once inspection is done. It would be a days work. It would just be to update everything and bring it up to today's...
If I was doing this job I would start all over. I would demo all that out and get the power company involved to get a new meter socket installed outside then run new wire into a new MAIN panel. If it's just a "typical" house - 200 amp panel would be fine. You can always add a subpanel later...
I bought rustoleum the professional series from Menards. I think I did my 1200 sq. Ft floor for around $300. They sell an etch cleaner to clean the floor with before epoxy. It cleaned a lot of my stains up. The floor looks pretty good for $300 and works as it should.