A few questions

[Buccaneer]

I have seen overlay discussed here and am not quite sure what it is. From reading and searching it seems like it is something like this: bet t50 to win t100 with a 50% win rate would be no overlay, bet t50 to win t500 with a 50% chance to win is an overlay of t450, bet t50 to win t500 with a 25% win rate is an overlay of t225. Is this the right idea or not.

I occassionaly play in single table trnys. Today I played in a multi. It was a only $1 and had about 140 people in it. I know it depends but will a $5+1 play much different than the $1.

How many times assuming normal play is it neccessary to risk ruin to in a $5 trny of about 150 players?

For a first trny book do I want to get Uncle Slanskys Trny Poker?