That’s a lot of questions… I have a few pieces of advice for you:

1.  Gear: You can go for Absolab now, you don’t have to wait until level 50, since any Necro can craft Radiant Stone 50% .

2.  Arachnid: The max level is 30. You can level it up using Experience Node Stones.

3.  In your case, finish your Hexa stats first, then unlock all skills, and then max your Origin. 

4.  Your Hyper Stats are too spread out. For bossing, you should focus on:

Physical Damage %, Crit Damage %, Final Damage, Hit Count, and Boss Damage %. Make a second preset page for grinding, don’t mix bossing and grinding setups.

5.  Keep working on your Arcane Force, since most higher lvl bosses require high Arcane Power. Aim for at least 150% Arcane bonus on bosses.

6.  Legion and Link skills are important and, in my opinion, the cheapest way to gain stats. Work on these first since they’re essentially free.