Photosynthesis

After the sun is placed, trees earn light points unless they’re in the shadow cast on the side opposite the sun; shadows are cast by trees onto same-size or smaller trees (Small = 1-space, Medium = 2-space, Large = 3-space). A tree taller than a shadow-casting tree is not shadowed and receives full light points (p.3).

At the start of each round’s Photosynthesis Phase the player with the First Player Token moves the sun clockwise to the next position (skipped on the very first round), then players count and add light points based on that new sun position (p.2–3).

No — actions (except buying) activate the spaces involved, and you cannot perform more than one action on the same space during your turn; specifically you cannot plant a seed and then grow it or grow a tree and then use it as the origin for a seed in the same turn (p.3–4).

Planting distance depends on the size of the origin tree: 1 space from a Small Tree, up to 2 spaces from a Medium Tree, and up to 3 spaces from a Large (Tall) Tree (p.3).

Growing costs are Seed→Small 1 LP, Small→Medium 2 LP, Medium→Large 3 LP; collecting (ending the life cycle of) a Large Tree costs 4 LP and lets you remove the Large Tree and take the top Scoring Token of the pile matching that space’s soil (p.4).