the 1065/1120S question indicates that you need professional help. if you filed an S-Corp election properly and timely then you have to file an 1120S and also a final 1065 also, doing new builds and selling may be a trade or business resulting in ordinary income, not capital gains. so last year that income could be self-employment income for each of the partners. SE tax is about 15% and not paying could result in substantial penalties for them. there may be tax consequences to converting from a partnership to S-Corp. if the shareholders (assuming you properly elected S-Corp) perform ed services for the Corp they should likely have been paid a salary. failure could result in significant penalties
if the $ value is high enough, you may be required to use the accrual method not the cash method of accounting.
better you have a pro look into this before you file than the iRS after you file. no one can be sure whether you need to file an 1120s./1065 or both. the S-election could have been faulty. the iRS will actually notify you but that may not occur until after the tax return due date.
I'm not saying you actually have tax issues. that has to be determined by someone that can look over the entire activity and get answers to questions that they think are relevant
