Sickpotter is exactly correct on point a) and much more succinct than I can ever be. On point b) however, I believe Sickpotter may have misinterpreted your question so I have to disagree with his answer. It is also possible that I am misinterpreting your question so he may be right and I may be wrong below. In any case, I will put in my two cents:
In the case of a), players are often confused by the "reds blocking other reds" scenario you are suggesting. Here is the best way that I have found to think about it:
For the purpose of awarding a "free ball" following a foul, one red may not be the cause of interference for striking the extreme edges of another red. So you must use your imagination...select the red ball that you are wondering, "Can I see the extreme edges on either side of that red?", then, in your mind, remove ALL the rest of the reds from the table. If THAT red is the only red on the table, can you now see the extreme edges of it? If the answer is "yes" (like it presumably is in your stated scenario), then there is no free ball awarded. Theoretically, you would need to go through this mental exercise for every single red ball on the table, but practically speaking, of course, it is generally quite obvious which one or perhaps two red balls may or may not allow for a possible free ball.
In the case of b), I am interpreting your statement of "the striker to play again from the resulting position" to mean that the balls are NOT replaced to their original position according to the "foul and a miss" rule. It doesn't matter if the cue ball appears to roll within a millimeter of where it was originally. The non-fouling player is required to request the referee to "put them back" (and a courteous player will add, "please") and if the referee thinks that the cue ball is resting exactly in the right spot anyway and nothing else was affected, he will touch the cueball with his fingertip and, as if by magic, they are now back in their original position. If on the other hand the next stroke is played from the "resulting position", there is no call for the "three miss and loss" rule because a different stroke has been played even if it appears to be very, very similar.
On a related note, personally, I have noticed that many players are confused by the various contexts in which the term "snooker" is used. Technically, the definition of "snookered" is:
Section 2. Definitions
"...when a direct stroke in a straight line to every ball on is wholly or partially obstructed by a ball or balls not on. If one or more balls on can be struck at both extreme edges free of obstruction by any ball not on, the cue-ball is not snookered."
...and then there are a whole bunch of boring qualifiers added onto that.
and this is exactly what you refer to for purposes of a free ball. If you cannot see both "extreme edges", then the cue ball is effectively "snookered" by definition.
But this definition of "snookered" has nothing whatsoever to do with losing a frame after three successive misses but people often seem to somehow put those two things together as in "It can't be a loss because the ball was snookered". The loss of frame following three misses is based on what is known as "central full ball contact". Imagine connecting the centers and edges of the two balls concerned with straight lines. If you can roll the cue ball without any interference to connect with the object ball like this, then "central full ball contact" is possible. Say the last three object balls are on the table, cue ball is on the brown spot, the blue is on its own spot, and the pink and black are on either side touching the blue toward the middle pockets. Blue is "on" and "central full ball contact" is available. If you "foul and miss" blue three times, you lose the frame despite the fact that, by definition, the blue ball is snookered. It really has nothing at all to do with a "snooker"; it is just a matter of defining ball positions. If you can plainly see the center of a ball and still somehow managed to NOT hit it three times in a row, you will be punished severely.