thyroid looks OK. do you have a hormone panel and overal bloodpanel? its not just about the thyroid ofcourse
As for testosterone go for whichever you like, its all testosterone and only difference is how fast it is detached from the ester thus how often do you need to inject. the test molecule is the same always.
Lean gains yes 12 weeks or longer depending on your need, experience level, health, blood markers, goals with this etc. there is no minimum or maximum, your goals and bloodwork determine the length of any cycle.
T3: go for 50mcg this is good to give a boost, you dont want to overdo it.
focus on ketogenic diet, let carbs go. do a once a week refeed meal to reset ghrelin and leptin hormones. if you can do a hormone panel this is very important. also test CRP and liver and kidney values alongside full blood panel and iron/ferritin.