N-G: Devo set and top mage weapon.
D-G: Knowlegde set (if you can get one for a reasonable price) and top mage weapon +3 at least.
C-G:When I asked about it people suggested SoWD with Magic Power + Karmian set.
It worked ok until I broke the SoWD going for +4...
Since then I've used Karmian and +3 Homu /w Acumen. Works for me. It's a kind of a pvp setup as its build for casting speed but it's good for pve too.
Some people say go Demon set for pve. Might be good but it'll take your casting speed down a bit, so in those tight situations you might end up dead more.
Corrupted man is the pvp summon, used with transfer pain to give you better survivability. I rarely see a necro level with summon out, and I don't really know enough to give advise in that regard.
Since you are 40 i would say Homunkulus Sword with Acumen, enchant it to +3, and Demon Set, it gives a good boost to m.att, with the +4 INT modifier.
For B grade you may use a Sword of Valallah with Acumen and Avadon Robe.
What would be the play style to advice since i am 40
Young necromancers 40-52 have it kinda tricky. You can use Vamp claw (mana expensive, you'll rest a lot). But you can still use your old pre-necro nukes until ... they start to fail too often. At 44 you get Death Spike. This consumes cursed bones. There is a quest for them, you hunt monsters under Ivory tower. They also drop Manticore parts there, so if you want to earn 2 mil craft boots and sell :)
At 52 you get spell Curse Death Link. The less HP you have the more damaging it is. It's kind of dangerous, but you level very fast with it.
As for quipment - Demon set, extra MATK is good specially under 52 when you rely on old skills and Vamp claw (uses much mana, you want to get rid of mob ASAP). Homu witrh Acumen is standard. You can safely skip B-grade for PVE, Demon is still OK, but you can also get Avadon set for extra casting speed if you need it (PVP, or you find you 2-shot mobs without demon anyway). A grade is usually Dark Crystal or Tallum.