1. I solo leveled a support necro in Bestiary. I found that aurabotting is surprisingly effective as a regular necromancer. I was playing SRS with 3 Specters but in hindsight I would have leveled a zombie setup. With three dps auras you can make them delete everything just by shield charging through. You don’t even need to stop just charge full speed through maps.
It won’t (obv) be as fast as actual clear speed meta builds but it will be more than enough for you to feel like you’re not just dead weight. Once you’ve gotten a Prism, Vicatario’s, and Alpha Wolf then respec your ~10 minion talents into something else.
2. Generally, you are going for necro for a little bit dmg and speed or guardian for a little bit of defence. First of all grab aura reservation nodes. There are some core items for most supports in poe: Alpha's Howl, Prism guardian, as a chest i prefer Shavrone. First 2 are cheap even on league start, and for the chest u can use Solaris lorica as alternative early on league start. Even with dat kind of trash gear u can generally turn on 10 auras and its more than enought for early game.
3. I leveled as witch. Necromancer ends up with a bit more damage, Guardian with more defensive. Ascendant is a very healthy blend between the two. Ascendant is really the best choice imo. Your enjoyment is what is most important though.
Fill in the missing jewel with a watchers eye. Mine is discipline/haste/haste and i was very happy with it. Find something that fits you and your playstyle. Additionally, there are plenty of points I used because it fit my gear/group that you can swap out. If you want more updates, please keep eyes on u4gm.com which is the most reliable online game store to offer amounts of poe currency cheap.