How to remove Well Head?

I have a 50+ year old single pipe shallow well supplying potable water for my home. The well is about 20 feet from my home, and the piping terminates in my basement where it is piped into a shallow jet well pump. I suspect that the galvanized iron pipe used is at least 50, if not 60 years old. I am seeing chunks of what looks like rusted iron in my input filter. I decided to dig up the well head and replace the foot valve, well head, and piping leading from the well to the jet pump. I'm attaching a photo of the existing well head. It is about 4" diameter. Some questions for you pros.

1. How do I remove the old well head? Looks like it it pretty well corroded in the casing.
2. Is it likely to damage the casing when I do the removal?
3. Once I get the old well head removed, is there any maintenance I should do on the casing?
4. The current setup runs a copper tube into the basement to vent the well. I would like to change that by running a small diameter PVC pipe vertically out of the well head and vent through that directly above the well. That will also help to locate the well in the future. Any issue with just placing a 4" PVC pipe on top of the well head and running the vent pipe up through it above the ground?
5. The existing input to the jet pump has a check valve at the input to the pump, to keep the pump primed. Should I remove that?

Thanks for any and all help.

Do a little more digging a see what is below that. Any time you take something that old apart you have a chance of breaking something. I would extend the casing above gound and use a pitless adapter to attach the pipe. In most states casing below ground level is no longer legal.

Thanks for the response. I have now dug out the well head, and the new photo shows the well seal. I have been trying to pull out the well seal, but no luck so far. If you look at the photo, you will see where I broke off a couple of bits of the top of the seal. What should be my next step(s) to remove the old seal? I don't think I want to remove the bolts (even if I could), because the seal probably has bottom plates that would drop down into the well if the bolts were removed. Do I just keep beating on it and prying, or perhaps try to chisel bits off of it?

Thanks for any and all help.

Got the seal off. I did loosen the bolts, and it then could be pried out with a lot of effort. I measured existing pipe length, and it was 21 feet. Add another foot to get up to the pump, and the vertical lift is a total of 22 feet. I measured the depth of the well, and got about 21 feet from the head. That was a bit of a surprise given the 21 foot existing pipe length. The standing water level above the bottom of the well is about 7 feet. Question now is, how far down the well should I run my new pipe? All the literature I read says keep the foot valve at least 18 inches above the bottom of the well.

The existing well has worked OK for 27 years. But perhaps some of the debris I was seeing was because the foot valve was at the bottom of the well. Note that the water delivered by the well has always been clear.

With only 7' of water in the well, I would set the foot valve ass close to the bottom as possible. Maybe 6" off bottom.