Follow-up 1 - makes more sense and I agree.
Follow-up 2 - no. Basis is an individual shareholder matter. If you think about it, your K-1's never reflected any capital contributed in the past. So there are some items that impact basis and are not reflected on the K-1.
Follow-up 3 - Technically the instructions to form 1040 Schedule E page E9 states to attach a basis schedule to your tax return to support any losses taken. I have never done this and if the IRS wants it then they can ask for detail. Your final capital gain / loss does not get reported on the 1120S as it is an individual gain or loss not an entity gain or loss. Your final gain or loss as determined from your basis schedule, will be reported on Schedule D and the applicable form 8949.
*A reminder that posts in a forum such as this do not constitute tax advice.
Also keep in mind the date of replies, as tax law changes.