Yes you snip the ends off, yes it gushes out if you hold it upside down. The trick is to not hold it upside down unless there's a lamb latched onto it.

Unless you can handle just one lamb at a time, you do waste a little milk each feed until they're on, but it's not much. The worst thing is that the silly little bleaters always get it all over their faces while they're messing around being too excited to get latched on properly - and the mixed up powder feed irritates their eyes.

Others on here say goats milk is good; I haven't tried goats milk but my lambs do well on Jersey milk. If I feed 100% Jersey milk I give them 1.5x the amount of ewe milk replacer, or I can just use some Jersey and some ewe milk replacer. I believe they do much better on a diet which contains some real milk from animals on your own farm than on a pure packet version.
So I would mix some goats milk into their feed, yes, just a little at first, increasing so long as they're not scouring or anything, up to whatever proportion you are aiming for. Keep an eye on their condition - how easily can you feel their ribs - and if they are getting thinner, up the quantity. If they don't then put flesh on, reduce the proportion of goats milk.