1) I don’t see anything inherently wrong with pacing during davening- it is usually done in shteibel-type places. Also, to Daven Shmonah Esrei in a place where people could walk right through is not Lechatchillah.
2) I don’t know who people follow nowadays, but the Mishna Berura says that you’re supposed to Daven especially aloud. (except for the Shmonah Esrei, which just you are supposed to hear)
Try to find a Shul that is more grounded, like with pews- you may find yourself more concentration there.
3) Also, let us not forget that we daven most of Tefilla in the plural, so your Tefilos are more accepted that way, together.
Cellphones are a completely seperate story.