For the PBG kits, the 2.5mm notched fret file is perfect. In fact it 2.5mm will be fine for almost all guitars unless they have vintage frets (where 2mm is better) or extra wide frets (where 3mm is better). I have a 2.5mm one of the fancy notched files and a set of the other files but with a proper handle https://www.ebay.co.uk/itm/Fret-Crow....c100008.m2219

There really isn't any difference between them in term of operation or effectiveness.

But for the slightly wider frets, and any stainless steel ones, I find I use this file first https://www.amazon.co.uk/gp/product/...?ie=UTF8&psc=1 and then finish off with the slightly finer diamond files. despite being diamond, they don't work well on stainless frets, whilst that Amazon file makes them only about 2x the effort of normal steel frets, not 10x.

I'm going to get one of the triangular files as well.

P240 grit Wet and Dry is my most used paper for polishing the frets. Sanding the frets level leaves lots of cross-fret scratches. Unless these are removed, the frets will feel terrible and very 'scratchy'. You can drag an off-cut from a top E across each fret. If the scratches haven't gone you'll feel it catch. Once it doesn't, you can then move up the grits and then onto the Micromesh. I try and use the same number of sanding strokes per fret, in order to keep the fret heights the same. So maybe 50-100 of the P240 depending on how deep the scratches were (using a diamond levelling file leaves deeper scratches than P240 on a radius block), then 20 strokes of the other grits.