no the shortest interval is 5 minutes, but as I stated above if your are waiting for a hot message you can always click the button to sync manually.
There are 2 kinds of Windows Mobile devices. Smart Phones and PDA devices. I son't like the Smart Phones. If you really plan to send email from the device you will want a PDA for ease of typing. If smaller form factor is your thing then the smart phone may be the right fit for you.
There are MANY different devices you can get so research what is available to you. I love my Samsung i730. A lot of people are hyped up about the new Verizon Palm Treo which Verizon has an exclusive on running Windows Mobile (don't get confused with the other Palm treo line running on Palm OS).
The cost of the devices range from $100-600 USD depending on device.
I really liked the Audiovox 6600 model, but will warn you I encountered numerous problems withthe speaker emitting a high pitch sound constantly over time with the device, eventually making me want to smash it. Autdiovox has a new model out that looks really sweet, the 6700.
I hope you find this post helpful.
Regards,
Mark