2003 Honda Accord V6- Dash lights & other problems?

When I bought the car a week ago, Check engine, abs, exclamation triangle and brake light was on. OBD2 scanner read, catalytic converter codes A1 and B1. Tried clearing would not clear. Came home, while physical checking, saw a power steering circuit wire, leading to ABS control module clip (coming off from side wire harness) connector was disconnected. Fixed the wire. My battery wire was removed. After fixing replaced battery connector, CEL gone. Car was kept running for an hour, CEL came on again, this time with oxygen sensor codes.
Now driving the car, about 50 miles CEL hasn't come back on, still reads not ready on OBD2 scanner, and still the TCS, ABS, BRAKE and exclamation triangle on.
Any ideas?

Second- my radio is making a screeching noise- any diagnosis? It looks apparent there was a sound system which was removed, could be a potential culprit. Checked radio connectors- all seem fine.

The central lock doesn't work, and the power lock button doesn't work.

1994 accord sat for 4 years. Repair

So I've got a 1994 honda accord dx 140k miles thats sitting behind the house. Long story short, its missing its front and rear bumpers and pretty sure it will need a new drivers door. Battery needs to be replaced and possibly the alternator.

So first off, is it worth fixing? It ran fairly good before the parts got stolen and 140k miles isn't bad. I'm on a tight budget so if this is cheaper than buying another clunker ill fix this up.

Also is there anything i can check or repair myself before buying the parts to see if it's worth it?
Nothing big but anything i could potentially learn online. I've got a lot of time on my hands. Its been turned on once in the past 4 years (about a year ago) so i'm sure itll need some new fluids, brakes.
And would i need a mechanic to do the bumpers, door, possibly alternator or could i manage that myself with some online help?

Maybe a total cost guesstimate from someone who knows a bit about these old hondas?

I lost my car key, have no replacement or duplicate?

I have a 2001 honda accord, the key is chipped. Is it cheaper to have a locksmith come and fix it? They said it's be 125 dollars for a new one and the service. Is going to the dealership going to be cheaper or more expensive?

My Air Conditioning doesn't work, but it makes a loud hissing sound?

First off, this is an air conditioning problem with my Honda Accord 2001 EX, 4 cylinder 2.3 liters.

Okay, here's the problem. Since last summer, i've had to put freon in my car, so i get AC pro, connect it and put freon, then everything is fine. This summer, i did the same thing, the air worked for a bit, so i turned it off. I later used it that day again, turned the car off without turning off the air. The next day, i mistakenly left the AC and the heat on at the same time, because it was cold. Now It doesn't even blow cool air anymore. I tried everything. I even tried putting more freon, but the needle on the AC Pro is now in the "red" zone, which means not to put anymore. Trying to fix the problem, i went on the highway with the AC switch on and kept driving. It sounds like the compressor comes on, then goes back off by itself, it comes on again and goes back off by itself. Later while i was still driving, i started hearing a loud hissing sound which turns back off when i turn off the AC. Any help?

Car makes loud noise when accelerating at high speeds?

My car is a 98 Honda Accord with 151k miles. I had this car for couple of years. A year ago, i had a check engine light came on and several days later, my car started making loud roaring noise when driving at high speeds. Accelerating feels weak. The higher the speed, the louder it gets. When i got the check engine light code read, it says something about "CAT" and emission controls. I don't remember the code now. I drove the car few days a week since then but now i want to repair it. I want to know what could be the problem? Catalytic converter failure perhaps? The noise seems to come from the centre of the car, not the engine. The car run fine under 40MPH speed but gets louder the higher the speeds. If i was driving at 65MPH, its so loud that it's hard to hear other passengers talk in the car. Any ideas?

I don't want to pay $100 for simple diagnostics dealers ask for. I want to know so i can repair it in a cheaper shops.

Symptoms:

Loud noise at high speeds.
Loss of power when accelerating
Check engine light.