The first and third picture are a kind of dermestid beetle and a sheet on these insects is at http://extension.colostate.edu/topic-areas/insects/carpet-beetles-5-549/  It is probably one of the smaller species, such as the varied carpet beetle or some other Anthrenus species.

Dermestid beetles are extremely common insects that may likely be found somewhere in most any Colorado home. They are scavengers that feed on dead insects, lint, and sometimes grain products. They do not bite.

The middle image I do not think is an insect. It is difficult to see detail but I d o not see legs, antennae or segmentation of the body that I look for to try and identify an insect from a picture such as this.

There are some things that do bite, and some things that cause symptoms that resemble insect bites. These are discussed in the sheet http://extension.colostate.edu/topic-areas/insects/mystery-bites-and-itches-arthropod-and-non-arthro...