Hello,
That's great that you woudl like to switch to Cari.net for your dedicated server.
Let me try to answer your questions as best as I can.
1) Yes, you can access your Windows server through Remote Desktop.
2) You have full root access to your server, you may install any programs that you wish. You can install MailEnable, however I would have to point you to the following links.
Acceptable Use Policy
Terms of Service
Opt-In Standards
3) Build time- access time depends on the server you want. We say that the server will be up in 24 hours, however servers are usually up within a couple hours.
4) If you are paying monthly there is no contracts. If you wish to cancel your services just delete your server from your account and submit a case for your account to be closed. To stop your card from being billed, you must cancel 6 days before your next billing cycle.