1.Stats: Should Furfrou get a stat boost, Evolution, Mega Evolution or nothing?
Furfrou can possibly get a stat boost, but a plus +10 would make it similar to Malamar, which wouldn't make much sense without a pre-evolution.
An evolution would make a lot of sense, but it would have a worse ability and more min-maxed stats.
A Mega Evolution would be extremely gimmicky and would not work.
2.Should Furfrou get more abilities?
Yes. Furfrou has only one ability, which is no longer a signature ability. Cute Charm, Illuminate, Intimidate, Moxie, Reckless and Wonder Skin would be potential abilities.
3. Should Furfrou get more moves?
Yes, Furfrou has decent movepool, but it can be much much more larger. Slack Off is the most obvious one, followed by Play Rough, Elemental Fangs, Elemental Beams, Nasty Plot, Teeter Dance, Copycat, Flatter, Focus Energy etc.
4.What additional typing Furfrou can have?
Dark, Fairy and Electric are the obvious ones. Psychic and Ground are the lesser obvious ones.