Travelling to US while I-129 in process

HR is about to file my I-129 for an L1. Can I still travel to/from the US while this is in process? I heard it can take 2-4 months, and I can't be away from our head office for that length of time. Plus my job involves traveling to conferences/meetings regularly all over the US.

Will it jeapordize my application if I continue to travel to the US until the application is approved?

Also - do I need to advise NEXUS that an application is in process, or only once its a done deal.

Any advice would be greatly appreciated!