Yes, there's a couple ways to do that. However, I would suggest using the speed dial feature. It's really easy and gives you 1 button access to your top 9 apps. (And dtwo button access to your next 90 apps.

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Just browse the start menu, find the app you want and highlight it. Press the Menu soft key and then select Speed Dial. Enter the number you want to use (1 is reserved for voice mail). Then from your home screen just press and hold that key to launch that application.
To change the start menu, there is a registry setting that says what the first page or two of the start menu should contain. This is designed so the carrier can make sure that their app is right at the start and easy for people to find. You'll have to search the forums for the reg key, I can't recall what it is. But changing what's listed here will order the start menu the way you want. A lot of the tweaks programs have this in them too. Like Tweaks2K.
EDIT - I just searched the forum and it should be the following registry key.
HKCU/software/microsoft/shell/startmenu/order