The speed of the kick meter has to do with the kicker's or punter's overall rating. The higher the rating, the slower the meter goes. Kick a FG with say David Akers who's rated 90 or so and then kick a FG with a 50 or 60 rated kicker and you'll see the difference. This has been around since 2k1 so it shouldnt come as a surprise to anyone.
And I advise against using a position to create a player in a different position unless they are interchangeable. Here's my setup -
QB
RB / FB
WR / TE
C / OG / OT
DT / DE
OLB / ILB
CB / SS / FS
K / P
For those who may be confused, the above is the setup I use when needing to overwrite players for one position that has no one left. For example, if you need to create a WR but have no one left to overwrite, you can edit a TE and then switch him to WR. The secondary is the best because you can almost never run out of players to overwrite. In my 2k7 roster, I did have to edit a few DT's into OT's because I had no one left but I tested it out and havent come across any problems. However, when I created my 2k6 roster a year and a half ago, I remember creating WR Reggie Brown for the Eagles by using an OL. Well, during the coin toss, instead of the starting QB and the LWR being in the coin toss, it was McNabb and an OL. The coin toss is always the starting QB and LWR for the home team and the starting QB and the LCB for the defense. If this ever changes, you have a roster problem.
And puja21 is correct when he says that changing a kicker or punter into another position affects his overall rating or vice versa. I remember overwriting someone into P Donnie Jones and his overall rating wasnt would it should have been. Bottom line is that you should at first, use the same position for the player that you want to add but if that's not possible, use the other position that can be interchangeable with the one that you're creating. For example, if you want to create a RB but have no one left, use a FB and just switch his position. If you have no FB's left either, you've got a problem.