Quick Question; thanks in advance

Alright, i have read most of the stickies/posts and have some what of an idea of what is needed. I have not found a post with my exact iphone firmware however so i am curious if there is another route for me. I have an iphone 3g firmware version 3.0 modem firmware 04.26.08 currently both jailbroken and unlocked. I was considering updating and was looking into the iclarified guides. However there seems to be a lot of fine print. Am i able to simply follow the guides to get my iphone jailbroken/unlocked? I know at one point i will be asked to update my band to 06.15, but the guide states that i would only need to do so if over 05.14 (if of course i need to unlock.)

Would my iphone 3g work well at my current baseband at 4.21, or am i better of upgrading to another version? If so which and is there a specific guide i can follow? Thank You

Guide i have been following: iClarified - iPhone - How to Jailbreak and Unlock Your iPhone 3G Using RedSn0w (Windows) [4.2.1]

You need to use custom IPSW (Pwnagetool 4.2)

Do NOT use redsn0w or greenpois0n, these tools will NOT prevent your baseband being updated to 05.15

It should work perfectly fine with 04.26.08 on iOS 4.2.1
Do you have a SHSH saved for iOS 4.2.1? Apple no longer signs restore requests for iOS 4.2.1

Thank you. Regarding the shsh, no i do not have any stored. I have not looked into any of this since i jailbroke/unlocked my phone and that was around the time the 3.0 firmware unlock was released. As i read it, it is impossible to get an shsh for 4.21 now and usually signatures are only given for a limited time. So would that make updating to 4.21 impossible? Or anything for that matter?

The 3G iPhone doesn't validate shsh in hardware so not having a saved SHSH isn't so bad as it is with the 3GS and newer devices. There are ways around the SHSH requirement on your device.

Apple only started soft-shsh for the iPhone 3G with iOS 4.0

Thank you. Alright, originally i was going to let it sit at 3.0 but there would be too many things i would miss out on; such as mms. Im currently using simple mobile and would love to continue doing so.

As i understood it, i would need to download the 4.21 firmware n pwnage, use custom ipsw (i would assume, only mac?) regarding the shsh, what would be the best way to bypass it on my 3g; problem free way? Thanks in advance.