Obstruction vs interference

Question
Two part Question:  Situation one. My team is on defense, the batter hits a pop up toward first almost dead on the base line.  My first baseman goes for it then pulls up because she sees the runner coming straight at her, the ball drops in front and rolls foul (first base never touched it) the other coach is yelling at her girl saying, "You run through that first baseman, you own that basepath."  In my mind, I'm pretty sure that if my first baseman had made an attempt on the ball and the runner collided with her and the ball dropped, it would be interference, correct?

Second situation, I have a runner on first stealing to second.  Catcher throws the ball off line towards first base side of second base bag.  Short stop fields the ball in my runner's base path before ball gets to her.  My runner head first slides into the SS and is blocked about 3 to 4 feet from the bag.  SS then catches ball and tags my runner.  Ump calls her out. I argued obstruction but he said it was incidental contact and not a malicious attempt to block base.  I didn't take the argument any further but after I thought about it later in the day, isn't that by rule, Obstruction?  Rule states that fielder can not be in base path until she has possession of the ball.  It doesn't say anything about malicious attempt or incidental contact.  I'm wondering how I may have stated my argument differently or if I did the right thing by keeping my mouth shut?  Isn't that by rule, about as clear cut as obstruction gets?

Answer
1. Yes, possibly malicious contact based on severity of contact.

2.  Text book example of obstruction.

Reread the second question.  I will continue my answer.  First, if the umpire doesn't know the rule you are in a bad place to start.  When I talk to an umpire about a call, I might start with:  Why wasn't that obstruction?  When I received the answer you did I would ask something like:  When did the rule change to allow the defender to be in the way of the runner prior to receiving the ball?  You would get some answer that doesn't make sense based on the rules.  Next question would be, I think you may have the application of the obstruction rule wrong.  Will you talk to your partner about it to see if he/she understands differently?

There is never a problem with a respectful, calm interaction with an umpire.  If they don't know the rules, there is nothing you can do about it.  If the avenue exists, you can give the umpire a poor rating, contact their assignor and let them know what happened or contact your AD and let them know as well.

Based on your description, I think you did all you can.