To REST or to SOAP for mobile applications?

I'm toying around with J2ME applications running on multiple mobile devices. Since I want them to run on most mobile phones I settled on Midlets. One of the questions I was musing is how to do the data communication with the back-end. Despite the "chattiness" of the data I already decided, that I will use XML as the data format (less hassle with diverse sources) and web services as the delivery method (the telcos who charge per kilobyte bribed talked me into that).
To parse XML in a Midlet you can use kXML or kSOAP. A few questions remain I haven't found an answer yet. Maybe someone can point me to answers or hints:

1. Can I use gZIP from Midlets?
2. How to integrate SMS (to trigger a pull) with a Midlet?
3. Should I use REST or SOAP for the communication? REST seems to be simpler but SOAP is better supported in Domino Designer.
4. How do I integrate HTTPS into a Midlet?
5. Can I access and transmit the Phone ID (IMEI) using Midlet?

A seasoned J2ME developer probably could recite the answers before breakfast, but they are new to me.