Well let's first talk about the pole, that's the easy part. If it's a standard C-band dish, and it sure looks like it is, it will take a 3½" outer diameter pipe, and if you want to put a 12 foot dish on it someday you need it sticking at least 6 feet out of the ground, maybe seven feet if you get deep snow. Now where I live, with my soil conditions and the fact that I don't live in a hurricane-prone area, I have never sunk a pole more than about five feet into the ground, using an old fashioned posthole digger, and I generally use four or five bags of concrete (if you can return the unused ones I'd buy a half dozen, just in case). I think a good rule of thumb in my area is you want at least as much pole in the ground as you have above the ground. But my soil is nor mucky clay or subject to liquification, and we have excellent drainage. You will get all kinds of advice on this and some people will want you to use enormous amounts of concrete for a pole, and that may be necessary where they live and with their soil conditions. Where I live, it's mostly hard-packed sand (compacted by centuries of tree roots) and sticking the pole five feet in the ground and using four or five bags of concrete has always been sufficient (depends in part on if they are 60 or 80 pound bags). Also you will also have guys tell you the pole can turn in the concrete if you don't weld some scrap metal to it, which may be true if you get smooth galvanized pipe but if you get a rusty pipe from the junkyard the chances if it actually turning are pretty low, barring a hurricane or tornado. Still, if you don't have a welder, somewhere on the part that's going into the concrete, take a sledge hammer and try to beat it into a more or less oval shape - that will also help keep it from turning once the concrete is hardened. Or if you have a powerful enough drill, you could drill a hole through it and stick an old bolt or a piece of rebar or something through the hole.
The pipe itself will cost you an arm and a leg if you buy it new (not really, but they aren't cheap and you may have trouble finding one). I've had the best luck at a local scrap metal junkyard. They nearly always have some lengths of 3½" OD pipe lying around somewhere and they sell it by the pound, in my area it usually works out to around $15 per pole. Bring a tape measure to check the length. Use a wire brush drill attachment to get off any heavy chunks of rust and then when your are down to light rust you can spray it with either Rust-Oleum Rust Reformer (best if you are going to apply a top coat of spray paint later) or Rust-Oleum Rusty Metal Primer (which is a bit cheaper but I don't think it actually converts the rust, I think it just seals it in so the rust can't get any worse. But I may be wrong). There are other brands of that stuff but Rust-Oleum is the easiest to find around here and one of the local stores usually has a pretty good sale on it every summer. I generally use the Rusty Metal Primer on the pole if I have any, and the Rust Reformer on the rusty parts of the dish and mount (it can also be used on the pole). Once you have done whatever you want to do with the rust, you can sink the pole, pour the concrete (making sure the pole is perfectly plumb - check it with a level several times on at least three sides of the pole) and wait for it to harden. Pro tip - prior to digging the hole dig a trench back to the house and run a length of cheap irrigation pipe (the black stuff that comes on 100' rolls, the 1" size is probably adequate unless you are going to be pulling several cables), put a plastic bag on both ends to keep water out, and when you dig the hole for the pole tape one end of the irrigation pipe to the hole and pour the concrete so it covers a section of the pipe. This not only helps protect your wire when you are mowing or if you are digging in the area, but makes it much easier to run the cable or to add more cable (if, for example, you go from a single to a dual output LNB). After you pull the cable use silicone caulk to seal the pipe ends.
Admittedly I take the approach of using the least effort possible when sinking a pole but it has never come back to bite me yet. I do think some guys get very ridiculous with the amount of concrete they use, but maybe they have a cement mixer or just enjoy mixing concrete in a wheelbarrow. I don't, so I tend to take the more conservative approach.
You will in all likelihood want a new LNB. I would think twice about using a PLL LNB on a 10 foot dish because they can potentially overload on very strong signals. It depends on what you are trying to get. If you are going after the only mux I know of that actually benefits from a 12 foot dish the yes, for that you probably do want a PLL LNB. But if you are going after a signal that maxes out your receiver's signal strength then the PLL LNB just MIGHT be a bit too much. They are great for a 7½ foot dish or smaller, and many users have them on 10 footers, as I say it just depends on what you're trying to receive. All I will say is that I have used both PLL and non-PLL LNB's and I have found that the PLL's work best on the smaller dishes or if you are trying to get 16APSK signals, but that's just my experience, YMMV.
The positioner may or may not still work, it depends on two things. One is whether or not it has rusted to the point that's its frozen (which is quite possible if no one's maintained it for years) and the other is whether it has a pulse-count control that's compatible with modern controllers. I am not the person to give advice on that though, because I much prefer multiple fixed dishes and in fact only one of my dishes has a positioner arm on it, and even it is currently locked down on a single satellite.
I will say that from your pictures it doesn't look like the dish is in horrible shape. It needs cleaning, some wire brushing and a liberal application of Rust Reformer on the rusty spots, followed by a top coat of paint, but I've seen worse. You made a good find with that one. I would check the rim to make sure it's not rusting out anywhere, especially if it's made of steel. Be a bit proactive about treating rust spots as they appear and you should get years of service out of it.
I don't think the WISP antenna will be an issue as long as it's not pointed directly into your dish. If you suspect it is causing issues, try cutting the power to the WISP transceiver and see if your satellite reception changes.
If you have any problems figuring out how to re-assemble it, just post pictures of what you have up so far and the parts you have left, and we should be able to tell you what to do next. But I think you'll find that once you get the mount on the pole, and then the dish on the mount, everything else will be rather obvious. It will be much easier if you have a helper or two when trying to get the dish attached to the mount (one or two to hold the dish sections in place while the other positions and attaches the bolts).
Hope this helps!
But that is a decision you can make sometime down the road, as long as you have something that works for now.
