Unions, dispatch, and which camp you end up at

Indirectly, yes -- because it changes who your employer is, and camp assignment follows the employer/project, not the union itself. A building-trades dispatch (IUOE 955, UA 488, LiUNA 92) sends you to whatever signatory contractor and project needs labour that week, which could put you at any operator's construction camp. A direct Unifor-represented job puts you specifically with Suncor or one of its named contractors, typically Suncor-area lodges. A non-union or CLAC-represented contractor job depends entirely on which project that contractor is currently staffing.

The first three are traditional building-trades "dispatch" unions -- you register on an out-of-work list, and the union sends its own members to whichever signatory employer needs labour for a project, which can change month to month. Unifor Local 707A works the opposite way: it's a bargaining unit tied to specific employers (mainly Suncor's oil sands operation), so you get hired by that employer first and are represented at that one workplace, not dispatched around between projects.

Contact the specific local directly -- each one runs its own list and process (see the table above for numbers). Generally you'll need to already be a member or be accepted as one, and most locals require periodic check-ins (IUOE 955, for example, requires a monthly check-in) to stay active on the list.

Not always -- it depends on the specific employer and project. Some oil sands construction and maintenance work is unionized through the dispatch locals above or through CLAC, some operations work is unionized through a direct bargaining unit like Unifor Local 707A, and other roles (especially with non-union contractors) are not unionized at all. Check the specific employer or project rather than assuming either way.