Link to Global Fields like you can with the entries fieldtype Is there any way to link to a global using a field in a entry form, much like you would use the "Entries" fieldtype to link to entries?
Not directly. You could have a dropdown of all the global set handles (use Dynamic Fields Plugin if you don't want to maintain this dropdown manually), and then in your template fetch the global set from its handle with getSetByHandle:

{% set globalSet = craft.globals.getSetByHandle(entry.globalSetHandle.value) %}
{% if globalSet %} {# could conceivably be null #}
  ... {{ globalSet.someField }} ...
{% endif %}