SIM Unlocking my iPhone, a few doubts!

Hello, i'm new to the forum and was wondering if you guys could help me answer some questions. Im planning to unlock my phone to be able to use it with a regular cingular sim card, first i will activate my phone using the iphone activation tool from hacktheiphone.com, after that i want to jailbreak my phone following the "10 steps to modding the iphone from hacktheiphone.com as well, and finally i will follow steps 11-18 on using the cingular simcard (the easy method) form hacktheiphone.com once again.

My questions were the following:

1- First of all, do the steps I plan to take sound right, or am I doing something wrong?

2- Once I perform these mods, will I be able to update my phone using software sync when updates are released from apple without losing all the modifications?

3- If one of these days they release a software unlock from either iphonesimfree.com or other party, will these modifications prevent me from downloading this unlocking software and fully unlocking the phone?