By the way, I only want the wireless for a mobile phone device, most probably an iPhone (I don't need a whole bunch of anti-Apple people telling me to get something else

As I understand it I get a SIM card with which:
a) I won't be able to make outbound calls on the GSM network at all.
b) Outbound calls will be done entirely through some sort of VOIP mobile app.
c) Incoming calls will use GSM and thus won't count towards the wireless data usage.
d) I can port an existing mobile number for use in this way.
e) I have 2 add-on packs with my ADSL service; 100 calls for $5 and 50mins of mobile calls for $5. Will outbound VOIP calls from the mobile device also come from these packs? For example, in one month I could make 20 mobile VOIP calls and 80 calls using ADSL2 VOIP and still pay the same $5? In the same manner I could also mix and match mobile-mobile VOIP and ADSL-mobile VOIP for a total of 50mins and still pay $5.
f) Assuming the answer to e) is yes. How far does the 100Mb get me? Assuming I do no other Internet activities on the phone other than VOIP I believe this is about 10 hours of talk time.
g) Uploads are counted on the wireless plan.
h) Normal GSM based SMS is not possible from the mobile.
i) I can still receive normal SMS.
j) SMS would, of course, be possible using the phone's browser and Exetel's 'Manage SMS' web page in the member section.
k) There's a mobile app for sending SMS, which is probably just a cutesy interface to the aforementioned web page.
l) SMS costs are therefore 5c each or I could get the SMS add-on pack if I send enough of them to make it worthwhile.
m) I will be SIP registered from two different devices (mobile phone + ADSL/VOIP all-in-one modem) simultaneously. Does this matter? Which phone rings if someone tries to dial my DID?
Thanks in advance,
Rob H