To answer your first question, there are a couples of solutions.
1. In the main prefs, select buttons from the pulldown menu on the top right side of the screen. Here you can reprogram one of your hard keys to "applications" and this will display the launcher when you hit that key.
2. You can a add a 3rd party app called buttons-T if your treo doesn't already have buttons-2 right beneath the buttons options in your prefs or treo button which is a similar app but gives you 3 sets of hard keys to configure your apps.
Buttons-T:
http://palmgear.com/software/showsoftware....fm?prodID=40595
treobutton:
http://palmgear.com/software/showsoftware....fm?prodID=40243
Your answer to question #2 is:
No, not on the native launcher. Possibly with a 3rd party launcher but I haven't seen any.