Can fielders do this? 2 situations

[Tap]

Speaking ASA SP.

1. I just recalled that, about 10 years ago when I played OF, with a runner on 1B and less than 2 outs, the batter hit a ball to me that I knew I could not catch on the fly. I screamed "I got it" and acted as though I was going to catch it on the fly. The runner from 1B hesitated and I short-hopped the ball and almost threw him out at 2B for a force. After the inning, the umpire told me he would eject me if I tried that again, but he did not explain why he had a problem with what I did. I was not an umpire then, but I thought he was wrong. Is there anything illegal about this? I guess technically it could be verbal obstruction or unsportsmanlike conduct. How many umpires would call this?

2. Secondly, how about a first baseman acting as a cut-off with a throw coming from the OF on a base hit, with a runner trying to score from second. If the first baseman lets the throw go home, but acts as though he caught it and maybe even fakes a throw to second to keep the batter-runner from advancing past first, is there anything illegal there? I don't think that would be obstruction. Anyone disagree?

Just trying to anticipate these situations if any players try it when I'm calling. And I also play some and play 1B, so I'm most interested in that scenario.