Sorry I didn't address this sooner.
1) Yes I have. I have also been in on bovine kills with lots of caliber/bullet combinations. The .44 works, it just doesn't produce the "hurt" of the bigger calibers. I've used a number of them on bovines. The .45 Colt loaded hot is pretty good. The .480 has served me well on a number of them, to include the biggest bovine I've ever taken. With the right bullet they are all suitable, I just prefer making a bigger impression if possible.
2) I've had both the .500 Linebaugh and .500 JRH for quite some time. There are a lot more good bullets available in .500 versus .510. The .500 Linebaugh is typically loaded in the mid-30,000 PSI range, the .500 JRH we load in the high-40,000 to low-50,000 PSI range. The fat Linebaugh case eats a lot of cylinder wall, and I don't recommend loading the .500 Linebaugh anywhere near the operating levels of the .500 JRH. Frankly, when facing something big, heavy and mean, I want as much reliable velocity as possible. However, the .500 Linebaugh is still one of my personal favorites.
3) Not that I noticed. I thought it might be an issue and it absolutely was not. Hire a good "meet and greet" outfit to collect you at the airport and get you through the bureaucratic pain, then they whisk you off to a hotel that sits behind a wall with barb wire. It's in their best interest to keep you safe and whole.
Hope this answers your questions.