@Roy Marks for CT, there's several real estate groups on facebook that would be a good place to start if you wanted to sell your property on your own.
Working with an agent is ultimately your decision. I would probably recommend one if you don't have a good pulse on the market or if you want to outsource all of the work to list the property. If you're willing to roll up the sleeves and know what the deal is worth, in my opinion an agent isn't necessarily a must with the big perk of saving the realtor fee.
You do need to work through a title company or an attorney since it's in CT.
You will have to provide disclosures to the buyer, I would work with your attorney on this. Generally speaking though, selling "as is" puts a lot of onus on the buyer to uncover issues on the property.
As far as improvements, I'd focus on what you can do to the property to get the best ROI, every property is different in this regard. I wouldn't power wash a house that needs a substantial amount of money, why put lipstick on a pig? But if the property is in great shape and just needs a polish with a power wash / paint, that can be a great improvement and appealing for buyers. Curious what others think on roofs, but I think it's tough to get back your investment on that, unless it was an absolute necessity to make it qualify for financing. Personally, even then, I'm not sure I would do it.
If you have a cash buyer ready to roll, id work with both your attorney and the buyers attorney to get things properly under contract and close out the deal.
For pricing, agents can be a big help with this, or you can try to run comps yourself to get a feel for what the house is worth. You can also hire an appraiser to independently evaluate what the property is worth for a fee, usually several hundred dollars.