Hi Calky
I agree with what LuborC has said up until now... The charts are generally a guide but ICM becomes very complex and ultimately you need to learn to play without the charts and adjust on your own...
My advice if you really wanna get good at SNGs and ICM is download ICM trainer lite and do all the lessons... this will give you a great understanding of all the "what's" and "why's" in ICM... next downlaod the ICM trainer and practice... When practicing, aim for 95% and up... use the charts when practicing and see some of the differences...
When playing, take note of the hands that you are not sure of and post them in the hand-posting section... just convert the hands and post them and you will get different opinions and advice about different situations... This is probably your single most important tool to accelerating your progress...
With regards to your other questions... on the micro limits in push or fold mode I treat limpers as all-ins because if you push they will generally call A LOT of the time... so play hands that are OK to call...
$30 bankroll is not enough to play the $2.25 games yet... it's far too easy to go bust with >14 buy-ins so either deposit some extra, use the TAF program or grind the $1.25 til you have enough...
And for your final question (I think)... when there is one raiser in front of you it can be complicated... for example with pocket pairs you can call some raises when you have the implied odds... Hands like AJ, AQ, KQ should be folded.... with AK sometimes it's a call sometimes it's a push.... but you learn all of this in the hand-posting section...
Ooooh... I wrote a lot... hope this helps and gluck...