Last question first. Yes, you can use a single equity account for both contributions and withdrawals and the year end net is the same. What you do need is another owner equity account to annually record earnings (since they pass through) and draw/contribution to.
Preferred is at least 3 equity accounts> Owner Equity, Owner Draw, Owner Contribution. Additionally several of us recommend making all three of these equity accounts sub accounts of a single parent equity summing account that is never directly posted to.
To clear annual equity movement (draw and/or contribution) you record a journal entry on the FIRST day of the new year, zeroing out draw/contribution into owner equity - this lets you report on an annual basis the payments that are not wages (for the S-corp election).
An LLC electing to be taxed as a corporation is still an LLC and its FEIN does not change. The election made by form 8832 designates the taxing status but it is still an LLC.
An actual true S-corporation is formed by election of a corporation (initially established as C) form 2553
Your operation is still an LLC and did not or should not have issued shares of stock just by electing to be taxed as if it had shareholders, the biggest difference being that you must pay reasonable W2 wages to the working members prior to distributing any other payments
