Tyre compounds.. ???

Currently using up my 003's and r10 rears , am i correct in saying that a hard tyre would be best suited for the colder days and the soft ones for hot track temp. If that theory is correct is it the hard tyre generates more heat when flexed compared to the soft one reducing cold tear issue.

Anyone else using the 003's or r10 rears . do you use them until it wears just just above the wear indicator or much below .. are they progressive in loosing grip when they get below the wear indicator ( is the wear indicator just for street legal use?)