for conversion from Coloricon to Newicon, i used Convert35Icon by Rafal Mania (as describe in my readme http://www.aminet.net/util/sys/Convert35Icon.lha
The only problem is that in fact newicon shouldn't do more than 93x93 pixel. Don't ask me how Convert35icon do the job... it's possible but not without danger.
A coloricon shouldn't do more than 20-22ko or when converting it to newicon your system could crash.
Less color a coloricon used, more luck you've to convert it without any risk.
Any other work on the icon are done using PPaint. I used Art Effect to resize Title pic but ADPro or any other Photoshop's like should do the job.
Have fun !
PS : You can find an update of Convert35icon now renamed to http://www.aminet.net/util/sys/ConvColorIcon.lha
but now it respect the 93x93 newicon restriction.