How long should I marinate the steaks?

Marinate between 1 and 24 hours depending on how pronounced you want the flavor. One hour gives good surface flavor; 3–4 hours is a practical sweet spot for most cuts. Avoid marinating much longer than 24 hours to prevent texture changes.

What temperatures should I target with a thermometer?

Use common internal targets and remove steaks about 5°F below your desired final temp to allow for carryover: rare ~125°F, medium‑rare ~130–135°F, medium ~140–145°F, and higher as preferred.