Can a fielder ever be charged...?

Happens a lot. A fielder may bobble a ball (error 1 allowing the batter/runner to reach first) and then pick the ball up and throw it away (error 2 allowing the batter/runner to take an extra base).

Yes, fielders can be charged with multiple errors on the same play

Yes, players can and have been charged with multiple errors on the same play.

Definitely. I think the record is four errors on one play (third baseman dropped popup, made bad throw to first, dropped throw from fielder trying to get runner coming in to third, then bad throw to home).

Two players have been charged with committing THREE errors on the same play.

Smead Jolly

"Jolley once committed three errors on one play. First, he let a ground ball roll through his legs; trying to play the ball off the wall, he let it roll through his legs; and finally he overthrew the cut-off man for the third error."

https://en.wikipedia.org/wiki/Smead_Jolley

Tommy John

1. Bobble ball trying to pick it up.

2. The throw to first.

3. The throw to home.

https://www.youtube.com/watch?v=IGLuJxvBhE8

I would say yes he could and probably would be charged with two errors.

Yes.

They sure can. Happened plenty of times before.