Preventive maintenance pump replacement

Hi, I'm going to replace my 25 year old deep well pump soon and a few questions come up:

Should I replace the "O" ring on the pitless adapter?
New adapters at Home Depot have some gooey lube/sealant on the "O" ring, what is the lube so I can get some?
My conduit has 3 wires, 2 hots and a common, I'd imagine I'd need a 2 wire pump as we don't count the common?
I have no idea how deep it is and I'll make a tripod to use a block and tackle to pull it up and re-tie it every 12 feet or so with a helper, will that work?
Does any one have anything good to say about a FloTec pump from the Depot?

Thank you for your help!

Is this a submersible pump?

How do you know what pump to buy since you don't know how deep the old pump is hung?

Home Depoe only sells 10 gpm pumps, no matter the horsepower. And NO I don't like them. One thing is for sure. If you buy a Flotec, you will never get out of practice changing them out.

bob...

I didn't build the place, the guy who did is dead. He's not answering questions on the depth of the well. I figured I'd pull it out and go buy what I need, there are plumbing supplys nearby if a Home Depot FloTec is NFG.

To replace the o-ring, you need one for the specific pitless you have, otherwise it probably won't fit exactly. Use a thin coating of silicone lube used for potable water, like Plumbers Grease.

The big box stores' stuff is nowhere near the quality you get from a pump dealer or pump supply house.

Three wires says a 2 wire pump, with ground, no control box.

If you have galvanized drop pipe, or the pump at say 500'+, you will need a serious tripod and the pipe will be in 20-21' sections that will unscrew. So you need to be able to stop and hold it to do that and to rest. That's a high tripod and large block and tackle. If it is PVC, it will be the same length threaded sections but not near as heavy. If PE pipe, you should be fine.

FloTec pumps... I guess the guys that sell them like them.