iPhone 7 camera lens replacement questions...

Camera lens on my iphone 7 is cracked, I have a few questions....

(1) I bought the "glass with frame" and not "glass only", can the glass with frame be replaced without opening the phone? If I need to open the phone to install the glass with frame, is there any way I can take the frame off so it's like the "glass only" so I can install without opening the phone?

(2) I'd like a clean method of replacing it (i.e. opening the phone and replacing it from the back) versus the guides on here advising me to crack the glass and glue one on top. But if I open the phone will it lose it's water resistant capability?

(3) The guide here lists it as medium difficulty, I've done some hard difficulty things without any issues, Is the easier method to just crack the glass and glue one on top? I am just afraid it might not appear clean (is anything glued ever clean?)

(4) Will my ex girlfriend's hair dryer she left here + tweezers work? I don't have a hot heat gun.