Are these ball or tie ends?

Despite a photo of ball ends in the description, they DO NOT have ball ends

I'm confused... why do "nylon classical guitar strings" say that they're silver-plated??? Are these nylon strings or steel strings??

They are nylon strings, its just the lower strings (E,A,D) are going to be "plated" with silver; all in all they are still nylon strings, not steel.

can I use this strings on a Jamine S35 guitar?

FYI: Steel-string guitars are built much heavier than classicals and it takes a steel string (with more tension) to "drive" the top of a SS guitar. If you use classical strings on it the strings won't begin to "drive" the top and it will sound puny to say the least. The dude who recommended trying "silk n' steel" strings is absolutely right. That is a cross-over string often used on very old parlor guitars; those might give you some decent sound, but probably nothing like what a regular steel string would give you. Free info from a luthier.