The end of mission rules mention if Lorn has 1 or more strain tokens on him, the heroes get extra credits. I can't seem to find anything in the mission rules that would actually put these strain tokens on him. What am I missing?

It looks like Lorn is considered an object when you interact with him. (It took quite a while for me to notice as well.) The number of strain tokens on him correspond to the number of successes you have "stored" from previous failed attempts. Note that you can go down in successes if negative surges are applied to the test due to the mission rule.

Gotcha, forgot that putting strain tokens for successes was part of the rules and not just convenient bookkeeping. Thanks!

regarding the spend movement in this mission.

so my understanding is that u have to spend 1 movement to push lorn up to 2 spaces while adjacent to lorn. so does this mean they can spend 4 movement to push lorn up to 8 spaces in one go while being adjacent?

A hero can use the ability multiple times per activation, but each time the mission rule is used, hero needs to be adjacent. A hero could still move Lorn 6 spaces by spending total of 7 movement points if I picture the situation correctly.