If you think an elk is big on the hoof, wait until you try to deal with one on the ground. Particularly in warm weather, the carcass should be gutted and opened to allow air circulation and the start of the cooling process as soon as possible. It's just like field-dressing a deer on a really big scale.
If you are hunting with friends and are real lucky, your elk fell where a vehicle or a horse can get to the carcass. If not, you are going to have to do some serious heaving and rolling to get the job done. I carry a small block and tackle to help with this. I also carry a meat and bone saw. An elk can be disjointed with a big hunting knife but the saw is much easier.

The final step is cutting the elk up into transportable hunks to haul out. Again, vehicle, horse or backpack transport are the options that dictate how big the hunks should be.

Elk are big animals and logic seems to say "Big game; big gun." However, before rushing out to buy a new magnum rifle, stop and think. "New" and "magnum" create a new shooting situation.
The new rifle (and, likely, new scope) will usually handle and perform a bit differently than your current hunting rig. You need to take the time to get used to it.
Magnum calibers produce more power and usually a flatter trajectory. However, if you don't take the time to get used to the increased recoil and muzzle blast of the magnum, your shooting ability will suffer. This means not only that you can't take advantage of the magnum's extra range, but also you will shoot poorly at shorter range.
Most outfitters and guides say they would rather have a hunter use a lesser caliber that he can shoot well than a magnum that he can't. Calibers such as the .270, .280, .308 and .30-06, with proper bullets, are entirely elk-adequate at reasonable ranges.

After laying around all summer, both you and your retriever are likely a bit out of shape and out of sync. The retrieving breeds are easily trained and often actually get bored if you don't keep them interested. This leads to bad behaviors such as digging and chewing stuff up.
Though there is no substitute for good training, the best retriever work is a result of a strong bond between man and dog. Once this is achieved, your dog will "read" you and work almost on instinct to do what you want.
Your commands should be consistent and so should your attitude and body language. The same word, said the same way, every time is fundamental to successful man/dog communication. Discipline to correct a problem, not to vent your frustration.
A refresher course on commands, both basic and advanced, is the best way to tone up both your retriever and your relationship with a hard-working dog. Keep the first sessions short until you both get in shape.

It may not take a magnum to kill an elk but I prefer "magnum" bullets. By that I mean the strong "premium" bullets with controlled expansion. A big bull elk is a tough test for a bullet and if you don't get a wound channel well into the vital area, a wounded elk is often the result.
Penetration is the issue. Controlled expansion bullets better harness the power of standard cartridges for good penetration and with the faster magnum cartridges, they prevent premature bullet blow-up.
Sectional density (SD) is the relationship of the bullet's weight to its length. "Long-for-their-weight" bullets penetrate better and that's critical on a big, tough animal such as an elk. I like a SD of at least .250 for elk and other large game.
Bullet makers tend to make their heavier bullets in a given caliber a bit tougher in the expectation that they will be used on bigger animals. Lighter bullets may have more velocity but you sacrifice both SD and bullet strength.

If you hunt one area enough, the deer are going to know about it, particularly wise old bucks. If you use permanent or semi-permanent stands, erect them early enough for them to weather-in, absorb natural odors and for the deer to get used to them.
If you use a portable stand, take it in and out of the hunting area. Also take your seat cushion and other personal gear in and out with you. Leaving your scent-soaked stuff in a buck's backyard is sure to tip him off.
When approaching or leaving your stand, be careful with your scent. Do not grab or brush against trailside vegetation and it is best to wear rubber boots to avoid leaving you scent about the area.
If you hunt one stand a lot, the deer figure it and you out. Don't hunt from the same stand every day. The hotter that stand site is, the more you should rest it, hunting there only when the conditions are most favorable.