Let's say I would get assigned helos within the navy, after my time is up would I be able to get on with a guard unit that flies fixed-wing fairly easily? (Due to the mil experience)
If you get helos in the navy and still want to fly fixed wing, there are ways. You can go be a VT instructor or fly station C-12's for your shore tour. It's a long shot, but you can also put in for a community transition late in your first sea tour if your command supports it. Like I said it's a long shot, but we did have a guy from my helo squadron get picked up to transition to the growler. I did a sea tour in HSC, then a shore tour instructing in the VT's, then picked up FTS at a C-40 squadron. At this point I have over twice as many hours in fixed wing as helicopters. You may surprise yourself though and realize you love flying helicopters.
Another thing you may want to think about is how long it could take rushing guard units to get picked up by one. I've known a few guys that spent years rushing guard units all over the country, including my first two on-wings who went Navy after spinning their wheels trying to get picked up by guard units. One of them was enlisted in the guard. Both fly super hornets now and seem very happy with their decision.
If you are looking for the fastest way to a major airline, you should probably start rushing guard units that fly heavies and plan on spending some time at a regional.