I am assuming you are stuck in an APT, so find out what is causing the APT and address those issues. It may very well be just some tight psoas/hip flexors, but it could also be a host of other things as well.
The hip flexor/psoas stretching and glute strengthening will not hurt at all to do and from the sounds of you situation will only help. But it may not be the only piece to the solution. From the information you gave, other things I can recommend include some soft tissue work to your hip flexors/psoas and TFL. I'd recommend something more than just foam rolling if you are able to afford it. Also, I would ask to have your IT Band released as well, which I think will help out a lot.
Overall, my advice is to go for the hip flexor mobility and gluteal strengthening as your friend recommended, but also look for all around hip, ankle, and t-spine mobility along with some soft tissue work (ART, Graston, etc) and get a release of your IT Band.