77 Chevy Suburban C10 2WD 454 Questions

I am considering restoring my dad's 77 Chey Suburban C10 2WD 454 which is of considerable sentimental value to me. I just had all the control arm bushings replaced and a front end alignment done and that made a world of
difference in the ride and steering. There are alot of other things I know I need to attention to put it back into good working order. Please keep in mind that I live in Phoenix Arizona where it is hot as a blast furnace in summer. We also have dust storms from time to time and frequent blowing dust. The Suburban has about 140K miles on it and has a rear end ratio set up for towing. I don't intend to do any towing , heavy cargo or off-roading with it. Any inputs to these questions would be much appreciated.
1. I has been way too long since I had the transmission serviced and whereas there doesn't seem to be anything obviously wrong with it I'd like to get it serviced properly and have a good quality fluid. How do I find a place that will service it honestly and not act like I am Bill Gates when it comes to suggested repairs/service? I would think it needs new fluid, a filter, possibly a modulator valve? and a pan gasket. Anything else as part of standard service? Is Mobile 1 ATF worth looking into? As little as I know about trannies they could tell me my torque convertor is about to crap out and I would not know one way or the other...
2. I can see my differential has been leaking some and fear what shape the gears and axle bearings might be in. I figure if I open it up and there are any traces of metal in whatever fluid there is left, or wear on the gears then I will possibly have to have the axle bearings and or gears replaced? Or is it a case if they don't make noise then just drain it, spray it out with brake cleaner, new gasket, fill it and run with it? I have purchased Valvoline Synthetic Durablend 80W-90 gear oil. Is this a good choice?
3. I think the steering box is leaking from the shaft seals(looks like both steering shaft and pittman arm shaft. I see they sell seal kits I assume to fix this problem. Is this pretty difficult task? The guy at the auto shop says most shops won't do it because of liability issues.
4. Has anyone replaced the front main bearing seal on a 454? I almost replaced it when I replaced the harmonic balancer but just plain ran out of time and had to get it up and running. It was definetely leaking. Is this a big job once I remove the harmonic balancer?
5. The air conditioning has been inoperable for several years, so I figure it will require replacing all the parts. It is a single front unit. Where is the best place to look for compressors, accumulators etc that come at a good price and decent quality. R-12 is expensive and I can't service it. R134A is owner serviceable but is also less efficient so I hear. Any suggestions? Has anyone used Freeze 12? I would like to drive around next summer without having the back of my shirt soaked when i arrive :)
6. My driver and front passenger door hinges are loose. I've read where you can get replacement bushings and new pins. It looked like they enlarge the holes to fit the new bushings. Is this the way its done or are their old bushings that are just replaced?
7. Most of the window guides are gone leaving all my windows to ratttle. Is there a good source to find these guides / seals (including for the rear window, tailgate variety)?
Thanks, Bob

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