100% of 3 Pros
As others have mentioned, it depends on several things like where the project is based and what your role is. If you're junior and work on a phase of the project that doesn't require site visits, you may not travel. If you're more senior or working in construction administration phase (when the actual construction is happening) you will likely be on the job site. Sometimes you'll need to travel to interview with a potential client. If the project is local then you may have more opportunities to visit the site and attend client meetings. As for paying more, I can't say definitively but when I travelled for work as a commercial interior designer for 13 years, all expenses were paid (billed to client) and I received a daily pay "bonus" for time away from home from one company but not at others.
It depends. If you work for a company, they probably will combine this at the beginning of the hiring. They can (for example) keep the base salary and pay themselves for the costs of your displacement, or pay a slightly higher salary.