BG44K vs Techron vs STP

I read a previous thread about these cleaners and have some technical questions regarding them.

I have a 92 L Sedan Auto and fill up with 91 octane at ARCO every time. I don't know what kind of additives they put in their fuel. I'd like to clean out my fuel system and engine but don't know enough about these cleaners to choose one. Hopefully you fellas (and gals) can help me out.

1. What's the main difference between the 3 (BG44K, Techron, STP) that makes them unique to each other in terms of cleaning? How do they claim to do a better job than their competitors?

2. Where can I get them? I've seen STP at auto shops, and I know Techron is sold by Chevron, but I've never seen BG44k anywhere.

3. How much more does BG 44K cost compared to the others? (STP $5 range, Techron $10 range, BG44K?)

4. Exactly which parts does each cleaner clean? I know that different cleaners claim to clean different parts of the fuel/engine system (eg fuel injectors, intake ports, intake valves, combustion chambers, exhaust valves), do these 3 clean all of these or parts of these systems?

5. Which one or which regimen do you recommend is best for legends (or my particular year/model if it's different)?

A friend suggested that I start out with BG44K to do a thurough cleaning (he said it was strong stuff, stronger than the others), and then do maintenance cleaning with regular Techron every 3000 miles. And use BG44K once a year from then on.

He suggested a more economical alternative would be to start out with Techron Concentrate (stronger than regular Techron, but less than BG44K) and then do maintenance cleaning with STP Complete Fuel System Cleaner every 3000 miles. And use Techron Concentrate once a year.

Does that sound about right or am I getting it all wrong?

Is there anything else I should add in regards to additives?

Thanks in advance,
Dave.