Will we (or loved ones) become angels when we go to heaven?

No. Angels and human beings are entirely different creatures (“Therefore, since the children share in flesh and blood, He Himself likewise also partook of the same, that through death He might render powerless him who had the power of death, that is, the devil” Hebrews 2:14). Jesus said after our resurrections we will be like angels in that we will not be married ("For in the resurrection they neither marry nor are given in marriage, but are like angels in heaven.” Matthew 22:30). But this was a specific limited comparison. It wasn't an indication we'll become angels, or a statement that we will in general be angel-like. Angels will always be angels and people will always be people. Humans are eternally human. Death involves relocation to a different place and transformation into better humans, not into nonhumans. (“And not only this, but also we ourselves, having the first fruits of the Spirit, even we ourselves groan within ourselves, waiting eagerly for our adoption as sons, the redemption of our body.” Romans 8:23)