Bottom line is, you need a boundary survey at a minimum to get done what you want to do. You have bids. Choose the one you feel best about as far as getting done what you need done. After it's done, walk the boundary perimeter, locate the pins (the crew may have stuck metal wire w/pennants-colorful plastic flags-in the ground at them) and see if the survey you received matches what you find. Check the legal description on the survey against whatever paperwork you have. Hopefully the boundaries marked are where you suspected they are, and the legal description matches what the survey shows. Check with your planning/zoning dept. about the assigned zoning category. An AG (agricultural) district usually provides much latitude in what you're allowed to do.
ASAP is the 'time to correct any errors or omissions' which you believe there may be. Hopefully, that is not the case. If you have a neighbor whose 'parcel' is suddenly smaller than he expected, because your survey shows the contiguous boundary line for your and his parcels 'gives you his property' make sure that you take pictures of the pins and maybe use a Pythagorean theorem triangle to place some additional below-grade pins of your own, photographed and then buried, so if your pins are removed, replaced, or otherwise tampered with, you know where they were.
We had an urban lot where we did a whole-house renovation at the same time as one of our adjoining neighbors did. One day, a backhoe showed up and began excavating on our property. That would be great if it was someone doing work we contracted, but it was the neighbor's hired excavation contractor. I grabbed our recent sealed survey and a tape measure, and flagged down the excavator equipment operator. I told him he was excavating on our property, and I did not want him to continue. I asked him to show me the approved set of plans which he was supposed to be working off-of. He got them and either he was incompetent at reading them, or he was setting up a case of adverse possession. The structure was a CBS wall for which he was digging the foundation. My attempt to reason with the equipment operator was useless. He put the plans away and resumed his work. On our property.
I went inside and called the building dept. All I got was voicemail. I requested an inspector to come deal with the excavator. About a half-hour later, a city employee from the Building Dept. arrived. He got the excavator to shut-down his equipment. I stayed away, but within earshot. After a short time, the Building Dept. employee red-tagged the job, ordering all trades off the job. Our neighbor was not happy!
The Building Dept. required the neighbor to get a boundary survey along the contiguous line between us. That was done, but not right-away. Meanwhile, all work was suspended. The surveyor retained by the property owner placed their pins next to the pins from our surveyor. Excavation work continued.
When the excavation work was completed, the formwork was put in the trench, again, on our property. Another call to the Building Dept., another stop-work order, and relocation of the formwork to be on their property. By this time, our neighbor wasn't having much conversation with us. But we avoided encroachment of real property improvements by a neighbor, and we kept our land, ours. When the neighbor's property was nearly finished, work again stopped, and the parcel went to foreclosure. After nearly a year of vacancy, and without a c/o, it sold for over $2.2 million. The buyers had to close-out all the permits, and complete the unfinished work, including a complete landscaping site plan, to code. The city loves its trees. And we never saw her (the prior landowner) again.