1) https://na.finalfantasyxiv.com/lodes...3e7ccabefa9954 This is the most up to date information
2) Relinquishing your plot does not get you anything, by relinquishing the plot you basically just return it to the system for someone else to buy and get nothing back.
3) It takes 45 days for the auto-demolition to complete. You will get a warning by day 30 and unless you sign in and enter your house before the 45 days are up, the house will be demolished. Any items that are not transferred to the reclamation npc will be returned in the form of gil.