settings/applications/manage applications/ select app you don't want/uninstall/
You wont be able to uninstall apps on the ROM of course, but anything installed after the update can be removed.
You'll have to download an app installer for new apps. Place the downloaded APK file in one of the folders contained on the SD card eg./downloads ( done via a USB cable plugged into your computer). Run app installer and it should list all APK files. Depending on the installer, you may have to open the sub directory (folder) you stored the app in.
As far as I know, the only way to install apps on sd card in android is through the root. In other words you need a rooted phone - rooting on the x10 mini/pro hasn't been achieved yet.