replacing the screen is a mess... you have to apply adhesive on a very small surface between the thin upper display sheet and the frontal housing; it's likely that in the process you'll either spill some glue in a wrong place or apply too much of it, in which case gaps appear between the rim of the housing and the display sheet. Gaps often appear inexplicably at side bezels. I've done it 3 times, twice of which times the result was unusable. The third time was less of a disaster but did leave visible traces on the paint at the top and bottom bezel.
you can try using stickers with adhesive on both sides, but you'll need very thin ones. Putting almost anything on the surface under the side bezels is near guaranteed to leave gaps, but putting nothing there is also likely to.
If you do it, order a front housing + display in one. THAT is a very easy thing to install. Although you have to be careful prying the battery away from the old housing or it will swell or even open. You should probably heat up the glue before prying at it, although that's obviously also a risky thing to do near a battery.