Terraforming Mars: Ares Expedition

No — starting with the second round you place the newly chosen phase card rotated on top of the previous one and you are not allowed to pick the same phase two rounds in a row (p.10).

During Development each player may play one green project card, and if you chose that phase the cost of the card you play this phase is reduced by 3 MC (p.11).

Steel reduces the cost of cards with the building tag by 2 MC per steel and titanium reduces space-tag cards by 3 MC per titanium (they reduce the cost rather than directly paying it), and a card’s cost cannot be reduced below zero (p.12).

Yes — at the end of the action phase, if you are able to spend heat or plants for a standard action you must do so unless the associated terraforming parameter is already at its maximum (p.14).

In Production you gain MC equal to your MC production plus your TR; if you chose the Production phase you also get the phase bonus of +4 MC, and you similarly gain heat, plants and cards according to those productions (p.15).

Yes — during the end step you discard down to ten and gain 3 MC for each card discarded, and the rules also allow you to discard project cards at any time to gain 3 MC (p.16; also p.11).