Will my Windows XP applications (like Excel) run under Linux?
Yes, could run, thought Wine. But, I really recommend you to use one of many...
Yes, could run, thought Wine. But, I really recommend you to use one of many alternatives that are Linux Native. Like Libreoffice.
Where you could use a native Linux application, take use of native.
Libreoffice is an amazing application, and you will expend less time to use than from one that was migrating from MSOffice 2003 to 2007/2010 for example. Theres also proprietary applications that are complete clone of MSOffice, like WPS Office. But again, take a time using Libreoffice, you will really enjoy.