Been looking at land to build in southern new hampshire there are 2 lots that look decent only issue is they dont have their own road access has anyone had any luck with gaining access through other properties or working something out with the town?

Complicating this issue is the need to do a 10-31 due to stepped up value/capital gains tax on half of the land.  

Probably not an issue for seller financing, but make sure there are no prepayment penalties.You can calculate payment and balloon amount easily enough with excel or google sheets.

Is there specific layout of properties that help you be successful instead of forcing the issue on any property?

I would hate for this to be an issue.2.

Also discuss with the contractor the time expected for the project if its small, mid or large and if it needs permits and how long would it take for permitting and all, also payment terms, make sure you go with payment terms that are fair to you and the contractor (so many terms but most common is monthly based on completed work with an upfront for materials) and ALWAYS keep the last payment until project is closed (retainage) and you do your walkthrough and if there's any issues you write them down and provide the contractor with (punch list to release the retainer once they're corrected or fixed). read about how to deal with contractors and always ask for references but it really depends on how big the job is, personally I wouldn't spend too much time doing due diligence on small jobs such as door latches or shelving rather on additions, layout change and other scopes.Good luck!

NJ comes with its own issues.

Regarding using funds from your LLC property business, you'll need to consult with a tax advisor to understand the implications and any potential issues with this approach.

In other words, is legal action necessary? 

Insurance is a big issue and crisis now in Florida.