I always hydrate the fret slots, let the water permeate the board and "steam" the frets as I pull them out. This has proven to reduce chip out, especially on ebony boards, as much as possible...
The new fret wire should be .003" to .005" taller in height than the remaining good frets and certainly the same width. The remaining old frets should be able to give up to .005" in height, to withstand recrowning, polishings and still be tall enough for good playing height...
Along with bean or shot bags, I use a fret buck to help reduce vibration from hammering in frets. I hammer in frets so I can feel how tight the tang is in the fret slot. This protects against over compressing frets in the slots and causing a back bow...
A partial refret can breath new life into the 1st through 7th fret area that is most heavily used on acoustic guitars. When conditions are right, a partial fret job is the way to go...