I was sure this quick and easy conclusion was telegraphing the message of cancellation, but then the shooting is a cliffhanger so I am not sure what to think.
If anything, I'd think that if they'd been aware they were being cancelled, it would've motivated them to go bigger with the finale, not smaller. And the show's fate won't be determined for a while yet, so they would've had no way of knowing at the time this was made.
Does this series have a comic tie in series in which that story thread could resolve if the show is axed
No. There have been a few tie-in comics set in the MCU, but generally Marvel just relies on the films and shows to promote the comics continuity's versions of the characters. For instance, there's an
Agents of SHIELD comic that incorporates the characters created for the show, but is set in the main comics universe.
or does the cliffhanger pretty much guarantee another season?
Nope. Renewal and cancellation are business decisions based on production costs vs. potential profits, not storyline considerations.
Many shows have done cliffhanger endings and still been cancelled, leaving their endings unresolved -- and many shows have done conclusive series finales and still been renewed, requring them to come up with more material than they ever intended (e.g.
Supernatural).
One of my favorite examples of the latter is
Sledge Hammer, a sitcom parodying Dirty Harry-type tough cops. The producers thought they were sure to be cancelled after the first season, so they just decided "what the hell" and had Sledge accidentally blow up the city with a nuclear bomb in the finale -- and then the show got renewed!

They resolved the cliffhanger in the second-season premiere by claiming that the first-season finale had happened 5 years in the future of the rest of the series, giving themselves room to run for another five seasons. Of course, they were quickly cancelled and never got a third season.