You can buy a converter kit for most (if not all) welders. Its just a socket that needs fixing to the front of the machine, connect up the gas and the power and away you go.
depends if the machine has a gas solenoid or a gas valve in the torch Neo, if it's a solenoid then it's a fairly simple conversion but a valve in the torch like a lot of the low-end hobby migs isn't as easy to convert.
The only advantages are euro torches are quick and easy to change and they are cheaper than manufacturers' replacement torches of the same quality.
Further advantage is you can get a nicer quality euro torch than non-euro torches. Just nicer to hold when you get a good one. Also they tend to be better supported at welder and torch end so less tight bends and better wire feed.
Yep, a liner change on a euro torch takes just a couple of minutes. Also, if and when the torch gets tired or damaged, £40 buys you a good new one which fits in 30 seconds, no contest if used in a production environment where downtime costs money.