I think you'll find there are as many training methods as there are trainers.

Everybody does it differently, and some dogs need different methods than another dog. Personally, I try to teach the dog the basics of the sit, stay, down, but work really heavy on the 'leave it' and 'come'. I do everything on leash and only start the off leash process in an enclosed area. I also rigged up an old flexi-lead with some extra heavy fishing line and a light weight clip. The dog hardly knows it's attached and I use it for practicing recalls outside of a fenced area once I've proofed the dog inside the fenced area.
On my first Eskie, I taught him the 'front' for doing obedience trials and expected him, no matter where he was at, to come to the 'front' position and sit until told to move. He learned 'come as 'come here' which was to show up somewhere next to me but not necessarily into the heel position. That was just so I knew he was around. But if I said 'heel', he would come into the heel position and walk nicely by my side. But all of this took time and it was about a year before I could really trust him off leash.
You can use any terminology that you want for different commands, just make sure you and everyone else is on the same page. Older dogs can learn just as easily as a younger dog. Patience and practice under various conditions and places is a key. Start out with a place with few distractions and add them after the dog gets the idea of what you want.
Good luck with your training. Make training fun for the dog and always quit on a good note. If you get frustrated because something new isn't catching on, then go back a step and end your training session with an exercise the dog knows well, even if it's something as simple as sitting for a treat. Take a day off of training once in a while and just go play with the dog. But with any dog, household manners are a must and is ongoing training for the life of the dog. Just like a little kid, they will try to test and see if they can get away with something once in a while, but you have to remember that if you think it's cute once, it can easily develop into a bad habit. Eskies are especially good at using their cute little smile to get away with stuff.